The preparation method and application of aluminum alloy flux-cored wire for wire arc additive manufacturing

The preparation method and application of aluminum alloy flux-cored wire for wire arc additive manufacturing | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The preparation method and application of aluminum alloy flux-cored wire for wire arc additive manufacturing Bo Zheng, Shengfu Yu, Zhengyu Yu, Lun Tang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6699297/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Ceramic phase modification is a effective method to improve the performance of wire arc additive manufacturing (WAAM) aluminum alloy component. In this paper, a preparation method of ceramic aluminum alloy flux-cored wire was developed. An advanced apparatus was developed for the preparation of flux-cored wires. The preparation system comprises three integral units: a wire forming module, a drawing module, and a coiling module. The wire forming module features a configuration of three forming rollers and three closed dies, while the drawing and reduction module incorporates 12 sets of wire drawing dies with varying diameters, with each stage maintaining a controlled compression ratio of 20%. The fluidization properties of the core powder mixture were systematically examined, revealing that optimal powder flow characteristics were achieved when the constituent particles were sized as follows aluminum particles at 300 µm, copper particles at 250 µm, and silicon particles at 200 µm. The pre-heat treatment parameters for the aluminum strip substrate were optimized, with the process conditions established as follows heating temperature of 230°C, soaking duration of 120 min, and air cooling as the cooling method. Through a sequential series of 12 drawing and reduction operations, a 1.2 mm diameter Al-Cu-NiO aluminum alloy flux-cored wire was successfully fabricated. During the WAAM process employing the developed Al-Cu-NiO flux-cored wire, the process exhibited stable arc combustion, consistent droplet transfer, and minimal spatter. The developed flux-cored wire was successfully utilized to fabricate the aircraft skin, demonstrating high formability and suitability for such applications. Wire arc additive manufacuting Flux-cored wires Aluminum alloy Heat treatment Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 0 Introduction Aluminum alloy has become a critical material for lightweight design in aerospace, rail transit, and related industries, due to its exceptional specific strength, corrosion resistance, and excellent machinability [ 1 ]. Wire arc additive manufacturing (WAAM) has emerged as a key technique for fabricating large aluminum alloy components, primarily owing to its high deposition rate, high material utilization, and relatively low equipment costs [ 2 , 3 ]. However, aluminum alloy components produced using conventional WAAM processes often exhibit inherent limitations, such as coarse grain structures and elevated porosity levels, which can significantly degrade the mechanical properties of the deposited metal. These limitations present a major obstacle to the broader application of WAAM-fabricated aluminum alloys component in engineering [ 4 – 6 ]. Consequently, improving the mechanical properties of aluminum alloy deposited metal through WAAM remains a critical technical challenge. Researchers have developed various techniques to enhance the mechanical properties of aluminum alloy deposited metal produced by WAAM. Key methods include interlayer rolling [ 7 – 9 ], interlayer hammering [ 10 , 11 ], interlayer rotary friction [ 12 , 13 ], and interlayer friction stir processing [ 14 ]. Interlayer rolling, as demonstrated by Colegrove et al. [ 7 ] and Gu et al. [ 8 , 9 ], significantly refines the primary coarse-grained structure, achieving grain refinement, pore closure, and size reduction. Similarly, Fang et al. [ 11 ] proposed an interlayer hammering-assisted WAAM method for aluminum alloys, which increased dislocation density and improved tensile strength by 16% compared to as-deposited metal. These findings underscore the potential of plastic deformation techniques in enhancing the mechanical properties of aluminum alloy components. However, these methods require substantial downward forces on the deposited metal, necessitating equipment modifications and incurring high costs. Furthermore, the significant downward hammering forces impose severe process constraints, particularly for delicate thin-walled structures. Despite these challenges, the techniques offer promising avenues for improving the performance of aluminum alloy components in WAAM processes. Ceramic particle-reinforced aluminum alloy WAAM technology has garnered considerable attention due to its strong process compatibility and cost controllability [ 15 – 24 ]. Jin et al. [ 17 ] specifically incorporated 5 µm TiC particles during WAAM 2219 aluminum alloy. Their findings showed that TiC effectively prevented the segregation of Cu at grain boundaries, improved the interface compatibility between the matrix and θ'-Al 2 Cu, and reduced the system’s nucleation free energy. As a result, the grain size was refined to 18.4 µm, and columnar crystal formation was eliminated. Sinha et al. [ 18 ] introduced SiC particles into the interlayer during WAAM aluminum alloy, finding that the addition of SiC promoted the formation of equiaxed grains throughout the sample. This approach resulted in an improvement of 48 MPa in mechanical properties compared to direct deposition. Martin et al. [ 19 ] used nano-ZrO 2 ceramic particles as the reinforcing phase, observing a notable grain refinement effect. Similarly, Ren et al. [ 20 ] found that TiB 2 particles significantly refined the coarse grains in 2319 aluminum alloy produced by WAAM, suppressed Cu segregation at grain boundaries, and improved microstructural uniformity, thereby enhancing the mechanical properties of the deposited metal. These findings collectively demonstrate that ceramic particle reinforcement is an effective approach to improving the performance of aluminum alloy components fabricated via WAAM. However, the realization of the above method is mainly to introduce ceramic particle reinforced phase by interlayer coating method, which is difficult to accurately control the content of ceramic phase introduced into the WAAM process, and the coating method makes the manufacturing efficiency low. To overcome the limitations of conventional coating techniques, Sun et al. [ 25 ] developed a wire-powder WAAM system. This system incorporates an independent axial powder feeder that enables precise control over both the type and content of ceramic particles (SiC, B 4 C, TiC, WC) introduced during the process. In a similar approach, Song et al. [ 26 ] demonstrated the incorporation of B 4 C ceramics into 2319 aluminum alloy deposits metal through side-axis powder feeding in WAAM. While these methods achieve accurate control over ceramic particle quantities, they suffer from inherent drawbacks including powder trajectory divergence, susceptibility to airflow interference, and low powder utilization efficiency. In an alternative approach addressing these limitations, Sokoluk et al. [ 27 ] fabricated a novel 7075 aluminum alloy solid wire incorporating TiC np . Their methodology involved preparing composite materials comprising Zn, Cu, Mg, Cr, and TiC nanoparticles, followed by casting these composites into square ingots and producing 3.17 mm diameter wires through hot extrusion. Similarly, Liu, Langelandsvik, and Oropeza et al. [ 28 – 30 ] successfully fabricated aluminum alloy solid wires incorporating TiC np using the aforementioned process. This method offers significant advantages, including precise control over ceramic content and the elimination of the need for a side-axis wire feeding device. It should be emphasized that while this approach enables precise control of ceramic content and eliminates the need for a side-axis wire-feeding device. It presents notable drawbacks. The initial stages of wire preparation are highly intricate, and the associated costs incurred during trial-and-error iterations are substantial. It can be seen that how to realize the precise introduction of ceramic is an important technical problem, and it is urgent to develop a new method for the introduction of ceramic particles. Flux-cored wire involves wrapping ceramic particle powder with a metal strip [ 31 ]. The key advantage of this technology is its ability to simultaneously and accurately transport the strengthening element and matrix metal using wire as the base material. Significant advancements have been made in carbon steel flux-cored wire technology. Lyalyakin et al. [ 32 ] demonstrated the use of a 0.5 mm thick ST2 steel strip for producing high-carbon cored wire. Zhou et al. [ 33 ] utilized Fe-Cr steel strips with a 15% fill rate to fabricate high-chromium cored wire. Currently, most cored powder for WAAM are made of carbon steel. Few studies have been conducted on aluminum alloy flux-cored wire. Different from carbon steel flux-cored wire production, the preparation of ceramic aluminum alloy cored wires presents numerous challenges. For example, aluminum strips have low elongation and are prone to work hardening during drawing, making the wire prone to breakage. Additionally, the flux core powder in these wires has low fluidity and tends to agglomerate, further contributing to wire breakage. Therefore, it is essential to develop specialized preparation methods and devices for ceramic aluminum alloy flux-cored wire. In this paper, the aluminum strip method is employed to prepare special ceramic aluminum alloy flux-cored wire for WAAM. First, a mold, process, and device for aluminum alloy flux-cored wire preparation were developed. Then, the heat treatment process of aluminum strip was investigated. Finally, using an in-situ Al 2 O 3 ceramic aluminum alloy flux-cored wire for WAAM as an example, the composition of the flux-cored wire was designed. Development experiments were conducted, and the forming, microstructure, and mechanical properties of the deposited metal were evaluated. These findings provide a process and theoretical foundation for the development of WAAM flux-cored wire. 1 Aluminum-based flux-cored wire drawing preparation system The Aluminum-based flux-cored wire is prepared through a process involving an aluminum strip of specific thickness and width coated with core powder. This process consists of four main stages: raw material preparation, wire forming, drawing, and coiling. Raw material preparation involves several key steps, including aluminum strip cleaning, particle powder screening, drying, and flow ability testing. The wire forming stage specifically includes the roll forming of the aluminum strip. The detailed preparation process is as follows: the forming roller first shapes the aluminum strip into a U-profile. Subsequently, the conveyor belt drives the powder into the U-shaped aluminum strip. Finally, the sealing roller closes and overlaps the U-shaped strip into an O-shape, resulting in the large-diameter cored wire, as illustrated in Fig. 1 a. The drawing stage comprises multiple sequential processes. Through the coordinated action of multiple sets of drawing dies, the aluminum-based cored wire undergoes dimensional reduction until it reaches the target diameter, as shown in Fig. 1 b. In the final coiling stage, a winding machine and packaging machine are employed to wind and package the wire, producing the finished product. Notably, both the roll forming unit and the drawing reduction unit play crucial roles in the preparation of aluminum-based flux-cored wire. 1.1 Roll unit design The roll unit includes a forming roll and a sealing roll. The forming roller is used to roll the aluminum strip into a U-shaped to ensure that the powder feeding unit of the subsequent conveyor belt can fully fill the powder into the U-shaped groove. The sealing roller is used to close the U-shaped aluminum strip into a lapped O-type to prevent the powder core from leaking. The aluminum strip is plastically deformed under the action of the punch/die of the upper and lower rollers. The number and size of the rollers have an important influence on the rolling forming of the aluminum strip. The number of rollers significantly influences the trade-off between cost efficiency and material properties during aluminum strip processing. Utilizing fewer rollers reduces production costs and enhances processing efficiency. However, this approach results in excessive single-stage deformation of the aluminum strip, leading to elevated internal stresses that may compromise subsequent drawing reduction operations. Conversely, increasing the number of roller groups diminishes the internal stress levels in the aluminum strip, but at the expense of higher production costs and reduced operational efficiency. Therefore, it is necessary to design the roll unit. The aluminum strip employed in this study is 1060 pure aluminum, with a thickness of 0.8 mm and a width of 12 mm. The diameter of the cored wire after forming roll process is designed to be 3.8 mm, and the total elongation coefficient, denoted as L Y (The ratio of the cross-sectional area of the finished cored wire to the initial aluminum strip), is 1.67. The forming process is carried out using three groups of forming rollers, each consisting of an upper and lower roller. As illustrated in Fig. 2 a. The G1 forming roller transforms the flat 1060 aluminum strip into a slightly curved concave shape. Subsequently, the G2 forming roller further bends the concave strip into one with a larger curvature. Finally, the G3 forming roller bends the concave strip with a large bending angle to achieve the desired U-shape. The closing process is performed using three groups of sealing rolls, as shown in Fig. 2 b. The G4 sealing roller initially closes the U-shaped aluminum strip. The G5 sealing roller is then used to bend the sides of the partially closed strip, and the G6 sealing roller completes the process by forming the fully lapped O-shaped wire. According to the relationship between the total elongation coefficient ( L Y ) and the average elongation coefficient ( L J ) of each pass, as defined in Eq. ( 1 ). The value of L J is calculated to be 1.09. $$\:{L}_{J}=\sqrt[N]{{L}_{Y}}$$ 1 Where N represents the number of passes rolled by the roll, which is 6 here. In adherence to the principle of "Small at both ends and large in the middle", the process is designed to ensure the stability of the initial rolling stage of the aluminum strip and the accuracy of the final rolling stage. The elongation coefficients for the first ( L 1 ) and sixth ( L 6 ) passes are reduced by 20% compared to the average elongation coefficient, as calculated by Eq. ( 2 ). The elongation coefficients for passes two to five ( L 2 to L 5 ) are determined using Eq. ( 3 ). The calculated elongation coefficients for each pass, from L 1 to L 6 , are as follows: 1.072, 1.12, 1.12, 1.12, 1.12, and 1.072, respectively. $$\:{L}_{\left(\text{1,6}\right)}=1+0.8({L}_{J}-1)$$ 2 $$\:{L}_{(2-5)}=\sqrt[4]{\frac{{L}_{Y}}{{L}_{1}\ast\:{L}_{6}}}$$ 3 To evaluate the rolling validity of the designed roll, a simulation using finite element software, with the G1 forming roller as an example. The simulation involved a static universal module, where the upper and lower rollers were modeled as rigid bodies. Friction contact was employed to reduce computational workload, with a friction coefficient of 0.15. The aluminum strip was represented as a flexible body with a hexahedral mesh, ensuring accurate deformation analysis. The quadrilateral main grids were used to discretize the upper and lower rolls, enhancing the simulation's precision. As illustrated in Fig. 3 , the simulation results demonstrate that the designed G1 forming roller induces significant plastic deformation on the aluminum strip's surface, achieving good forming quality with flat edges. These findings confirm the practicality of the designed forming roller. Furthermore, the reliability of the design method underscores its applicability for the design and preparation of forming rollers. This approach not only validates the effectiveness of the current design but also provides a robust framework for future applications in roller design. 1.2 Drawing die design The drawing die was categorized into 12 distinct groups, each with a die aperture diameter of 3.2 mm, 2.84 mm, 2.52 mm, 2.24 mm, 1.99 mm, 1.81 mm, 1.66 mm, 1.53 mm, 1.42 mm, 1.32 mm, 1.24 mm, and 1.17 mm, respectively. The drawing compression ratio, defined as the ratio of the difference between the cross-sectional area of the inlet and outlet to the cross-sectional area of the inlet, was maintained at 21% for the first seven passes and progressively reduced to 17%, 16%, 15%, 14%, 14%, 12%, and 11% for the subsequent passes. Notably, the total compression ratio was meticulously controlled 20% and rationally distributed across each individual drawing process. This controlled approach effectively prevents wire fracture caused by excessive deformation, ensuring a stable and reliable wire drawing operation. The drawing die consists of four main areas: the lubrication area, the compression area, the sizing area, and the outlet area, with a total length (L) of 12 mm. The lubrication area facilitates the entry of lubricant into the mold hole, thereby reducing drawing resistance. The feed cone angle (θ 1 ) in the lubrication area ranges between 80° and 100°, with a recommended value of 90° based the research of Leng [ 34 ]. The length ( L 1 ) is calculated as 1.3 times the feed diameter ( D 1 ), determined by the specific mold used in this study. The compression area induces forced extrusion deformation in the aluminum wire. Its length ( L 2 ) is calculated as L 2 = L - L 1 - L 3 - L 4 . The cone angle ( θ 2 ) in the compression area ranges from 20° to 28°. Given that the final product is a thin wire of 1.2 mm, a cone angle of 20° is preferred for the small-angle compression area. The sizing area stabilizes the diameter of the aluminum wire and corrects any unevenness. Its length ( L 3 ) is 0.3 times the total length ( L ). The outlet area is designed to prevent scratches during the removal of the aluminum wire from the mold. The exit cone angle ( θ 3 ) ranges from 60° to 90°, with a selected value of 75°. The length ( L 4 ) is 1.3 times the feed diameter ( D 1 ). Based on the aforementioned analysis and calculation formulas, the key dimensions of each drawing die can be determined. Figure 4 illustrates the drawing die used for a wire diameter of 1.81 mm. Figure 5 a-d presents simulated equivalent stress distribution maps for wires drawn through dies with different aperture diameter (2.25 mm, 1.81 mm, 1.42 mm, and 1.17 mm). The analysis reveals a clear correlation between die aperture diameter size and maximum tensile stress. As die aperture diameter decreases from 2.25 mm to 1.17 mm, corresponding maximum stresses decrease progressively from 14.8 MPa to 7.23 MPa, respectively. The spatial distribution analysis demonstrates two critical findings. First, across all simulations, maximum stresses consistently concentrate in central regions exhibiting irregular radial patterns. Second,the simulation results confirm absence of wire fracture incidents, indicating theoretical reliability in die design. Figure 5 e shows the stress contour map of 1.17 mm diameter wire drawing process. It can be seen that the stress during the drawing process is mainly concentrated in the left area of the wire transversely close to the left side. The maximum stress area is the central area of the wire transverse (Blue area), rather than the transition area from large diameter to small diameter. This shows that the tube wall (Aluminum strip) of the wire is not the maximum stress during the drawing process. Therefore, the die is expected to ensure that the wire is not broken during drawing. In summary, the roll is designed and fabricated based on the extension coefficient of each rolling pass and the shape of the roll groove. The roll is made of cemented carbide, which possesses significantly higher strength and stiffness compared to the aluminum strip. The equipment units required for each stage are integrated into a cohesive system, and a production demonstration line for the preparation of aluminum alloy flux-cored wire has been established, as shown in Fig. 6 . 2 Aluminum strip preheating treatment process The rolled aluminum strip is prone to work hardening during the drawing process. The aluminum strip requires annealing before cored wire fabrication to enhance ductility and plasticity, preventing fractures during drawing. According to the standard GJB 1694A-2019 heat treatment requirements of wrought aluminum alloy, the annealing process of aluminum strip was optimized by orthogonal experiment method, and the heat treatment environment was vacuum atmosphere. L9(3 3 ) was selected to design the experimental scheme, and the three factors of the experiment were determined as follows: heating temperature A for 230℃, 270℃ and 310℃, holding time B fro 90 min, 120 min and 150 min, cooling method C (Three levels were air cooling, water cooling and water cooling (Quasi-level)). The response target is the elongation of the aluminum strip. Table 1 presents the experimental design and corresponding results. Using the elongation of the aluminum strip as the response variable, a range analysis was conducted following orthogonal test methodology. The results of this analysis are listed in Table 1 , where K 1 - K 3 represent the average elongation values for each factor at three levels, and R denotes the difference between K max and K min . A larger R value indicates a stronger influence of that factor on elongation. The analysis reveals that heating temperature has the greatest effect on elongation, followed by holding time, while cooling method (Factor C ) exhibits the smallest R value and thus minimal influence. Additionally, Table 1 identifies the optimal process parameters as A 1 B 2 C 1, corresponding to a heating temperature of 230℃, holding time of 120 min, and air cooling. Under these conditions, the annealed aluminum strip achieves its highest elongation. Table 1 Orthogonal test scheme and results of heat treatment of aluminum strips Sample Heating temperature A /℃ Holding time B /min Cooling method C Elongation D /% #1 230 90 Air cooling 21.8 #2 230 120 Water cooling 20.5 #3 230 150 Water cooling 21.6 #4 270 90 Water cooling 13.4 #5 270 120 Water cooling 20.3 #6 270 150 Air cooling 18.1 #7 310 90 Water cooling 10.2 #8 310 120 Air cooling 19.7 #9 310 150 Water cooling 14.2 K 1 63.9 45.4 59.6 - K 2 51.8 60.5 52.1 - K 3 44.1 53.9 48.1 - R 19.8 15.1 11.5 - Factor sequence A > B > C - Optimized compose A 1 B 2 C 1 - Figure 7 shows the metallographic diagrams of aluminum strip at holding times of 120 min under air cooling conditions, with annealing temperatures of 230℃, 270℃, and 310℃, respectively. As shown in Fig. 7 a, the initial rolled aluminum strip exhibits elongated fibrous grains that grow along the rolling direction, indicating a typical rolling deformation structure. As shown in Fig. 7 b, under annealing at 230℃, the fibrous deformed structure is replaced by an equiaxed recrystallized structure. This is due to the high density of dislocation defects in the rolled aluminum strip [ 35 ]. After annealing treatment, the material first undergoes the recovery stage, where vacancy density decreases, and with prolonged holding time, it enters the recrystallization stage. During this process, internal dislocations rearrange and induce nucleation, resulting in regular and uniformly sized grains. As shown in Figs. 7 c and d, when the annealing temperature increases from 230℃ to 310℃, the grain shape becomes more uniform with higher heating temperatures. However, significant grain coarsening occurs, and grain size gradually increases, which is particularly evident at an annealing temperature of 310℃. The optimal annealing parameters from Table 1 are used to anneal the aluminum strip. Figures 8 a-f show the reverse pole figure, grain size distribution, and pole figure of the annealed aluminum strip. These images were obtained using a scanning electron microscope equipped with electron backscatter diffraction. Compared to the initial aluminum strip (Fig. 8 a), the internal grains change from fibrous to equiaxed, and grain size increases from 13 µm (Fig. 8 b) to 33 µm, as shown in Figs. 8 d and e. As shown in Fig. 9 c, the initial aluminum strip exhibits a strong texture along the deposition direction (Y0) on the low-index crystal plane (100). The maximum pole density is 17.58, causing fibrous columnar crystals to form along the rolling direction. After annealing at 230℃, the fibrous columnar crystals transform into equiaxed crystals. As shown in Fig. 8 f, the maximum pole density on the (100) plane decreases to 16.56, indicating inhibited directional growth of fibrous columnar crystals and promoting equiaxed grain formation. It can be seen that recovery and recrystallization reduce dislocation density within the aluminum strip, leading to decreased tensile strength and increased plasticity and elongation. Figures 9 a and b show the stress-strain curves and mechanical properties histograms of the initial aluminum strip and the aluminum strip annealed at 230℃ for 120 min. The initial aluminum strip has a tensile strength of 114 MPa and an elongation of 4.8%. After annealing at 230℃, the tensile strength decreases to 67 MPa, while the elongation increases to 22.3%. Figure 9 c illustrates the fracture morphology of the tensile specimen of the initial aluminum strip. A small number of elliptical dimples are visible on the fracture surface. These dimples are large in size and depth, with a uniform distribution. After annealing at 230℃, the tensile necking of the aluminum strip increases, and the fracture morphology becomes honeycomb-shaped. Additionally, the number of elliptical dimples on the surface significantly increases, with a very uniform distribution, as shown in Fig. 9 d. Plastic deformation white tearing ridges form between the dimples, and the ductile fracture phenomenon is more pronounced. This improvement in ductility is due to the annealing treatment, which changes the grain structure from fibrous to equiaxed with uniform grain size. In summary, prior to the preparation of the ceramic aluminum alloy flux-cored wire, the aluminum strip undergoes annealing to ensure it achieves high elongation and tensile strength. The annealing process is carried out under the following optimized parameters: a heating temperature of 230℃, a holding time of 120 min, and an optimized cooling method involving air cooling. 3 The fluidity of the core powder The flowability of core powder plays a critical role in the preparation of aluminum alloy flux-cored wires. Figure 10 illustrates the powder flow behavior as a 1.99 mm-diameter wire passes through a drawing die with an aperture diameter size of 1.81 mm. The analysis reveals that the maximum flow velocity of the core powder varies significantly with particle size: 0.0943 m/s for 80 µm, 0.102 m/s for 150 µm, 0.104 m/s for 200 µm, and 0.111 m/s for 300 µm. These results demonstrate a clear positive correlation between particle size and flowability—larger particles exhibit progressively higher flow velocities, suggesting enhanced powder mobility with increasing granule dimensions. Analysis of flow visualization further reveals distinct spatial variations in powder flow behavior. As shown in Fig. 10 , the core powder exhibits higher flow velocity in the central region of the wire compared to areas adjacent to the outer wall. This phenomenon, consistent with findings reported by Yang et al. [ 36 ], arises from viscous resistance between powder particles and the pipe wall. Based on theoretical considerations, during the drawing process of the flux-cored wire, an excessively small powder particle size may reduce the overall fluidity of the core powder, particularly near the wire wall. This reduction in local powder fluidity can lead to increased frictional forces between the powder particles and the wire wall, resulting in increased loads on the aluminum strip. Consequently, this raises the fracture tendency during the drawing process and may ultimately lead to wire failure. Clearly, the particle size of the core powder plays a critical role in the successful preparation of the aluminum alloy flux-cored wire. 4 Preparation and application of flux-cored wire 4.1 Composition design of flux-cored wire The in-situ Al 2 O 3 ceramic aluminum alloy flux-cored wire serves as a critical material for WAAM aluminum alloy components, particularly those requiring enhanced thermal insulation and compressive properties. During the WAAM process, the flux-cored powder within the wire undergoes a metallurgical reaction, generating an Al 2 O 3 ceramic phase. This phase not only enhances the strength of the deposited metal but also significantly reduces its thermal conductivity. The alloying elements in the in-situ Al 2 O 3 ceramic aluminum alloy flux-cored wire include Cu, Mn, Ti, V, Zr, and NiO. Among these, Mn, Ti, V, and Zr play a pivotal role in ensuring the comprehensive mechanical properties of the deposited metal. Notably, during the WAAM process, NiO reacts with the aluminum strip to form both the Al 2 O 3 ceramic phase and Ni, thereby further improving the thermal insulation and compressive properties of the aluminum alloy components. Additionally, to enhance arc stability, a small quantity of NaF is incorporated into the cored wire as an arc stabilizer. The specific content of the alloying elements (W 1 ) in the cored wire is listed in Table 2 . Table 2 Design composition of Al-Cu-NiO cored wire deposited metal (Wt%) Cu Mn Ti V Zr NiO Al 5.7–6.4 0.2–0.4 0.05–0.15 0.1–0.15 0.05–0.1 ≤ 2 Bal. The diverse alloying elements present within the deposited metal are derived from the flux-cored powder contained in the flux-cored wire, facilitated through droplet transfer mechanisms. To achieve the precise composition of each alloying element within the deposited metal, as specified in Table 2 , stringent control over the elemental composition within the cored wire is imperative. The quantitative relationship between the content ( W 1 ) for each constituent element present within said layer alongside their respective concentrations ( W 2 ), may be expressed mathematically via Eq. (4): $$\:{w}_{1}={w}_{2}\ast\:\phi\:\ast\:\epsilon\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\text{(}\text{4}\text{)}$$ Where φ represents the filling rate of the cored wire, while ε denotes the transition coefficient of the alloying elements. During WAAM, the high instantaneous temperature of the arc may lead to significant burn-off of alloying elements in the flux-cored powder. As a result, not all alloying elements within the cored wire fully transfer into the deposited metal. To quantify this effect, a transition coefficient (ε) is introduced to characterize the efficiency with which each element transitions from the cored wire to the deposited metal. The experimentally determined transition coefficients for the alloying elements investigated in this study are listed in Table 3 . Table 3 Element Transition Coefficients Cu Mn Ti V Zr NiO 0.8 0.75 0.6 0.75 0.7 0.93 The ceramic aluminum alloy flux-cored wire is prepared by 1060 aluminum tape coated powder. The filling rate φ is defined as the maximum amount of core powder that can be coated per unit length by a U-shaped aluminum strip, which is constrained by the strip's width and thickness. Specifically, φ is calculated as the ratio of the mass of the powder core ( W 3 ) to the combined mass of the powder core ( W 3 ) and the aluminum strip ( W 4 ) over a 1-meter length of the strip. The filling rate can be expressed mathematically as Eq. ( 5 ) [37] : $$\:\phi\:=\frac{{w}_{3}}{{w}_{3}+{w}_{4}}\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:$$ 5 It can be seen from Eq. (4)-( 5 ) that the higher the filling rate, the greater the weight of the powder core, and the higher the content of each element in the deposited metal. However, due to the easy work hardening during the drawing process of aluminum alloy, the core powder of the flux-cored wire is too much, and the fracture tendency of the wire is greater. Combined with the previous test and theoretical calculation, the filling rate of aluminum alloy flux-cored wire is 15%. According to Eq. (4)-( 5 ), combined with Table 3 , the content of each alloy element except NiO in Table 2 is taken as the lowest value. The content of each alloy element in the cored wire is calculated as shown in Table 4 . The nominal content of NiO in the deposited metal of the cored wire is 2 wt.%. Table 4 The ratio of alloy core powder in flux-cored wire (Wt%) Cu Mn Ti V Zr NiO NaF Al 47.5 2.67 0.83 0.89 0.95 14.34 1 Bal. 4.2 The karl index of core powder The powder core is primarily composed of Al, Cu, and NiO. Based on the findings from multiple experimental trials, when the particle size of NiO is 50 µm, the resulting second-phase particles exhibit suitable dimensions and good bonding performance with the matrix. Therefore, following the control variable method, the particle sizes of the two ceramic components are first determined. After establishing the particle sizes of the ceramic powders, Al and Cu powders are identified as the primary factors influencing the fluidity of the core powders. According to the flux-cored wire composition in Table 4 , core powders with different particle sizes of Al and Cu are prepared. Specifically, in the first group (#1–#4), the Cu powder particle size is 250 µm, the NiO particle size is 50 µm, and the Al powder particle size varies sequentially at 150 µm, 200 µm, 250 µm, and 300 µm. In the second group (#5–#7), the Al powder particle size is fixed at 300 µm, the NiO particle size is 50 µm, and the Cu powder particle size varies at 150 µm, 200 µm, and 300 µm. Figure 11 presents the bulk density, tap density, angle of repose test results, and particle size screening process for the core powders. The fluidity test results for the mixed core powders with varying particle sizes are summarized in Table 5 . The Karl index FI is used to evaluate the fluidity of the core powder. When FI is greater than 70, it indicates that the core powder has good fluidity. When FI is less than 40, it indicates that the flowability of the core powder is very poor. When FI is between 40 and 70, the liquidity is moderate. The Carl index FI can be calculated by Eq. ( 6 ) [38] : $$\:FI=F1+F2+F3+F4\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:$$ 6 Where F1 ∼ F4 is the Carl index corresponding to the angle of repose θ rp , the degree of compression C p , the flat angle θ i and the uniformity U , respectively. The conversion relationship between the Karl index FI and the flowability index can be found in the national standard GB/T 31057.3–2018. According to Table 5 , the particle size of Al powder has the greatest influence on the particle size of mixed core powder. Under the limited process combination, for the Al-Cu-NiO alloy system wire, when the Al particle size is 300 µm, the Cu particle size is 250 µm, and the mixed core powder FI is 89, indicating that the Al particle size in the core powder is 300 µm. When the Cu particle size is 250 µm, the mixed core powder has good fluidity, which is beneficial to the preparation of ceramic aluminum alloy flux-cored wire. Table 5 Flowability index of core powder and corresponding FI Sample θ rp C p θ i U FI #1 37.4 16.1 44.2 10.1 73.5 #2 33.6 11.4 32.1 6.9 86.0 #3 31.3 10.2 31.8 6.4 88.5 #4 30.2 10.4 30.7 5.6 89.0 #5 38.2 18.4 41.3 11.8 71.5 #6 39.4 19.9 39.2 11.7 72.5 #7 37.7 18.6 39.1 10.8 73.5 4.3 Surface forming of flux-cored wire Figure 12 is the macroscopic morphology and schematic diagram of the in-situ Al 2 O 3 cored wire prepared by the above drawing-reducing method. From the cross-sectional view of the wire, it can be seen that the core powder is coated by the aluminum strip, and the wire presents a typical sandwich structure. The outer layer is a rolled aluminum strip, and the memory is the core powder particles. There are no obvious gaps and cracks on the surface of the wire, and the forming is better. The surface quality of ceramic aluminum alloy flux-cored wire is a critical factor influencing the stability of wire feeding during WAAM. The surface morphology of the SiC-containing ceramic aluminum alloy flux-cored wire was observed using a scanning electron microscope at 30× and 50× magnification, as shown in Figs. 13 a and b. As evident from the figures, the overlap formed by the closed overlap O-type wire is clearly visible. The wire surface is flat, smooth, and free of obvious scratches, pits, or burr defects. Compared to the commercial aluminum alloy solid wire (Figs. 13 c and d), the surface quality of the lapped O-type ceramic aluminum alloy flux-cored wire prepared by the drawing-reducing method is also superior. 4.4 Deposition processability of flux-cored wire The CMT-CYCLE welding mode was adopted. The shielding gas was high-purity argon and the gas flow rate was 20 L/min. Deposition current 85 A, voltage 9.8 V. Figure 14 presents the forming and surface roughness of the deposited metal from the cored wire. When the NiO content is 2 wt.%, the deposited strut exhibits stable formation, with a well-formed surface and a noticeable step effect. No defects such as pores or cracks are observed, as illustrated in Fig. 14 a. The surface profile of the rod was measured using a surface profile measuring instrument, with each rod measured three times. The surface profile fluctuation was found to be 55 µm. Figure 14 b shows that the surface profile fluctuation of rods deposited by different self-generated Al 2 O 3 ceramic flux-cored wire is consistently below 60 µm, demonstrating high smoothness. These results indicate that the cored wire prepared by the aluminum tape coating method possesses excellent formability. Figure 15 presents a full-cycle droplet transfer diagram of WAAM process using flux-cored wire. The arc ignition occurs through contact arcing, followed by stable combustion. Droplet transfer occurs in short-circuit mode with minimal spattering due to the excellent arc stability. This high stability performance is attributed to NaF additives in the cored wire. [Na] (ionization potential: 5.14 V) ionize more readily than [Al] (5.99 V) or [H] (13.6 V). During arcing, thermal decomposition of NaF produces abundant Na + , significantly increasing charged particle density in the arc plasma. Concurrently, the liberated F − combine with H + in the molten pool to form HF, effectively reducing hydrogen content in the deposited metal and suppressing hydrogen porosity. The results demonstrate that developed in-situ Al 2 O 3 ceramic aluminum alloy flux-cored wire enables stable arc maintenance and consistent droplet transfer throughout the WAAM. Figure 16 depicts the current and voltage profiles of droplet transfer during three consecutive cycles of rod made via WAAM using in-situ Al 2 O 3 ceramic aluminum alloy flux-cored wire. Notably, the interval time between each cycle is 200 ms, and the current and voltage remain relatively stable throughout the process. The peak change trend is consistent with the droplet transition characteristics presented in Fig. 15 , and the signal curve has no significant fluctuations. This consistency demonstrates the robust manufacturability of the developed Al 2 O 3 ceramic aluminum alloy flux-cored wire in the WAAM process. 4.5 Deposited metal composition of flux-cored wire Bulk samples with a size of 20×20×40 mm were deposited on 1060 aluminum alloy plate using developed aluminum alloy flux-cored wire with a nominal content of NiO of 2 wt.%. In order to prevent the substrate from diluting the composition of the bulk, the bulk with a height of 20 mm in the upper part of the deposited bulk was taken as the test sample, that is, the bulk with a size of 20×20×20 mm was obtained for testing the chemical composition of the deposited metal. The chemical composition of the sample was tested by ARL 4460 direct-reading spectrometer. Due to the unstable content of O measured by the direct-reading spectrometer, the content of Ni was used to evaluate the amount of NiO introduced. The test results are shown in Table 6 . Comparing Table 2 , it can be seen that the content of all elements in the deposited metal is close to the design value. Among them, the Ni content is 1.532 wt.%. The actual NiO content is 1.949 wt.% calculated by the relative atomic mass ratio conversion (The mass fraction of Ni in NiO is 78.6 wt.%), which is basically consistent with the design introduction. It shows that the deposited metal composition of the cored wire prepared by the aluminum strip method is in line with the design value, and this method is feasible. Table 6 The measured content of cored wire deposited metal (Wt%) Cu Mn Ti V Zr Ni Al Ⅲ 5.694 0.299 0.047 0.119 0.094 1.532 Bal. 4.6 Deposited metal microstructure and properties of flux-cored wire The microstructure of the metal deposited using an in-situ Al₂O₃ ceramic aluminum alloy flux-cored wire (composition: Cu: 47.5 wt.%, Mn: 2.67 wt.%, Ti: 0.83 wt.%, V: 0.89 wt.%, Zr: 0.95 wt.%, NiO: 7.17 wt.%, NaF: 1 wt.%, Al: residual) is presented in Fig. 17 . The deposited metal predominantly consists of equiaxed crystals, comprising α-Al as the primary phase and Al₂Cu precipitates dispersed within the grain structure. Additionally, a limited number of pores are observed in the deposited material. Scanning electron microscopy (SEM) images reveal a significant presence of Al₂Cu strengthening phases, which are evenly distributed within the grains of the deposited metal, as illustrated in Figs. 17 a and b.To further elucidate the internal phase composition of the deposited metal, a detailed characterization was conducted using transmission electron microscopy (TEM) and energy spectrum analysis. As shown in Figs. 17 c and d, the TEM images reveal the presence of nanoparticles within the deposited metal matrix. Energy spectrum analysis confirms the presence of a significant amount of oxygen (O) in addition to aluminum (Al) in this region. The nanoparticles consist of Al₂O₃ ceramic phases, which exhibit an ellipsoidal morphology, and Al₂Cu phases, which appear as platelet-like structures with an average size of approximately 50 nm. These findings demonstrate that the specialized aluminum alloy flux-cored wire for WAAM can be successfully prepared through a drawing and diameter reduction process, thereby achieving the desired compositional requirements. Table 7 summarizes the mechanical properties and thermal conductivity of the as-deposited metal fabricated using in-situ Al 2 O 3 ceramic aluminum alloy flux-cored wire. A custom-developed Al 2 O 3 ceramic aluminum alloy flux-cored wire was employed for the deposition process, specifically for fabricating the straight wall structure. The as-deposited metal exhibited an average tensile strength of 253.4 MPa and a room-temperature thermal conductivity of 88.8 W/(m·K). Table 7 Mechanical properties and thermal Conductivity of deposited Metals # Tensile strength (MPa) Average Thermal conductivity at 25°C(W / (m∙K)) Average 1 252.1 253.4 89.2 88.8 2 258.4 88.6 3 249.7 88.5 As demonstrated by the analysis, the chemical composition of the deposited metal derived from the in-situ Al 2 O 3 ceramic aluminum alloy flux-cored wire closely matches the design specifications. The microstructure of the deposited metal predominantly consists of α-Al grains, with the presence of Al 2 O 3 ceramic phase and Al 2 Cu phase, which collectively exhibit both favorable mechanical properties and relatively low thermal conductivity. 4.7 Application of flux-cored wire The aircraft outer skin has the following dimensional specifications: a height of 250 mm, a top outer diameter of 265 mm, a bottom outer diameter of 135 mm, and a thickness of 10 mm. The structural model of the component is illustrated in Fig. 18 a. The developed ceramic aluminum alloy flux-cored wire was employed to fabricate the aircraft skin. The substrate dimensions is 500 500×20 mm. The model was sliced using Eclipse software with a layer height of 3 mm. The WAAM process was conducted with a deposition current of 125 A and a deposition rate of 0.6 m/min. The aircraft skin fabricated via this process is shown in Fig. 18 b. It can be seen that the surface of the aircraft skin exhibits good formation quality, with no noticeable defects such as collapse or cracking. Non-destructive evaluation of the deposited metal revealed no significant defects, including pores or incomplete fusion, which can be attributed to the excellent arc stability and low spatter rate of the developed cored wire. Furthermore, dimensional measurements using three-dimensional metrology indicated that the deviation between the fabricated component and the design model is within ± 1 mm, confirming that the manufacturing accuracy meets the specified requirements. 5 Conclusions Aiming at the preparation requirements of ceramic aluminum alloy flux-cored wire for WAAM, this paper developed the preparation of cored wire, and formulated the drawing process of aluminum alloy flux-cored wire and the heat treatment process of aluminum strip. Taking the Al-Cu-NiO system ceramic aluminum alloy flux-cored wire as an example, the flux-cored wire was trial-produced and applied. The main conclusions are as follows : ( 1 ) In this paper, a roll unit composed of three forming rolls and three sets of closed rolls is designed. A drawing die with 12 sets of different diameters is also designed. The single compression ratio is controlled at 20%. The preparation equipment of aluminum alloy flux-cored wire composed of wire forming unit, drawing reduction unit and wire rolling unit is integrated, which can realize the preparation of aluminum alloy flux-cored wire with a minimum diameter of 1.2 mm. (2) When the particle size of Al is 300 µm, the particle size of Cu is 250 µm, and the particle size of Si is 200 µm, the core powder has high fluidity. The pre-heat treatment process parameters of aluminum strip were determined : heating temperature 230°C, holding time 120 min, cooling method: air cooling, after 12 drawing and reducing processes, the preparation of ceramic aluminum alloy flux-cored wire with diameter of 1.2 mm was realized. (3) The Al-Cu-NiO aluminum alloy flux-cored wire was developed. Using the developed Al-Cu-NiO flux-cored wire, the arc combustion is stable, the droplet transition is stable, and the spatter is small. The deposited metal is composed of α-Al and Al 2 Cu precipitates dispersed in the grain, and the in-situ Al 2 O 3 ceramic phase is nano-sized. The outer skin of the aircraft is prepared by using the developed aluminum alloy flux-cored wire, which has high forming performance. Declarations The authors have no relevant financial or non-financial interests to disclose. Conflict of interest The authors declare no competing interestss. Funding This work is supported by National Natural Science Foundation of China (51790174). Author contribution Bo Zheng conducted experiments, sanalysis, and wrote the manuscript; Shengfu Yu and Zhenyu Yu made contributions to research concept and manuscript preparation; Lun Tang assisted in analysis through constructive discussions. Data availability The data that has been used is confidential. References S. S. Li, X. Yue, Q. Y. Li, H. L. Peng, B. X. Dong, T. S. Liu, et al. Development and applications of aluminum alloys for aerospace industry. Journal of Materials Research and Technology, 2023, 27: 944-983. https://doi.org/10.1016/j.jmrt.2023.09.27 A. P. Nagalingam, M. Shamir, E. B. Tureyen, A. R. C. Sharman, O. Poyraz, E. Yasa. Recent progress in wire‑arc and wire‑laser directed energy deposition (DED) of titanium and aluminium alloys. The International Journal of Advanced Manufacturing Technology, 2025, 136: 2035-2073. https://doi.org/10.1007/s00170-024-14967-w A. Hamrani, F. Z. Bouarab, A. Agarwal, K. Ju, H. Akbarzadeh. Advancements and applications of multiple wire processes in additive manufacturing: a comprehensive systematic review. Virtual and Physical Prototyping, 2023, 18(1): 1-34. https://doi.org/10.1080/17452759.2023.2273303 A. G. Ortega, L. C. Galvan, M. Salem, K. Moussaoui, S. Segonds, S. Rouquette, et al. Characterization of 4043 aluminum alloy deposits obtained by wire and arc additive manufacturing using a Cold Metal Transfer process. Sciencce and Technology of Welding and Joining, 2019, 24(6): 538-547. https://doi.org/10.1080/13621718.2018.1564986 J. K. Wang, Q. K. Shen, X. D. Kong, X. Z. Chen. Arc Additively Manufactured 5356 Aluminum Alloy with Cable-Type Welding Wire: Microstructure and Mechanical Properties. Journal of Materials Engieering and Performance, 2021, 30: 7472-7478. https://doi.org/10.1007/s11665-021-05905-y Y. M. Huang, S. S. Hou, T. Sun, L. J. Yang, S. S. Li, S. B. Chen, et al. An improved model of porosity formation during pulsed GTA welding of aluminum alloys, Materials Science and Engineering B, 2018, 238: 122-129. https://doi.org/10.1016/j.mseb.2018.11.012 P. A. Colegrove, J. Donoghue, F. Martina, J. L. Gu, P. Prangnell, J. Honnige. Application of bulk deformation methods for microstructural and material property improvement and residual stress and distortion control in additively manufactured components. Scripta Materialia, 2017, 135: 111-118. https://doi.org/10.1016/j.scriptamat.2016.10.031 J. L. Gu, X. S. Wang, J. Bai, J. L. Ding, S. Williams, Y. C. Zhai, et al. Deformation microstructures and strengthening mechanisms for the wire+arc additively manufactured Al-Mg4.5Mn alloy with inter-layer rolling. Materials Science and Engineering A, 2017, 712: 292-301. https://doi.org/10.1016/j.msea.2017.11.113 J. L. Gu, J. L. Ding, S. W. Williams, H. M. Gu, P. H. Ma, Y. C. Zhai. The effect of inter-layer cold working and post-deposition heat treatment on porosity in additively manufactured aluminum alloys. Journal of Materials Processing Technology, 2016, 230: 26-34. https://doi.org/10.1016/j.jmatprotec.2015.11.006 S. Y. Zhou, J. Y. Wang, G. Yang, B. Wu, H. Xie, K. Wu, et al. Periodic microstructure of Al–Mg alloy fabricated by inter-layer hammering hybrid wire arc additive manufacturing: Formation mechanism, microstructural and mechanical characterization. Materials Science and Engineering A, 2022, 860: 144314. https://doi.org/10.1016/j.msea.2022.144314 X. W. Fang, L. J. Zhang, G. P. Chen, K. Huang, F. Xue, L. Wang, et al. Microstructure evolution of wire-arc additively manufactured 2319 aluminum alloy with interlayer hammering. Materials Science and Engineering A, 2021, 800: 140168. https://doi.org/10.1016/j.msea.2020.140168 R. Z. Yu, S. F. Yu, Z. Y. Yu, B. Zheng, G. Z. Yu. Effect of inter-layer rotary friction processing on porosity of arc-directed energy-deposited high-strength aluminum alloys. Journal of Materials Processing Technology, 2023, 316: 117951. https://doi.org/10.1016/j.jmatprotec.2023.117951 R. Z. Yu, S. F. Yu, Z. M. Wang, G. Z. Yu. Strengthening of wire arc additive manufactured aluminum alloy through interlayer rotary friction processing. Science and Technology of Welding and Joining, 2023, 28(9): 923-931. https://doi.org/10.1080/13621718.2023.2247271 C. S. He, J. X. Wei, Y. Li, Z. Q. Zhang, N. Tan, G. W. Qin, et al. Improvement of microstructure and fatigue performance of wire-arc additive manufactured 4043 aluminum alloy assisted by interlayer friction stir processing. Journal of Materials Science and Technology, 2023, 133: 183-194. https://doi.org/10.1016/j.jmst.2022.07.001 P. Jin, Y. B. Liu, F. X. Li, Q. J. Sun. Realization of structural evolution in grain boundary, solute redistribution and improved mechanical properties by adding TiCnps in wire and arc additive manufacturing 2219 aluminium alloy. Journal of Materials Research and Technolgoy, 2021, 11: 834-848. https://doi.org/10.1016/j.jmrt.2021.01.030 F. R. Chen, Y. H. Yang, C. Chen, Q. X. Wang, R. J. Xun. Effect of La 2 O 3 particle size on the microstructure and properties of Al-Si alloys deposited via wire arc additive manufacturing. Journal of Manufacturing Process, 2021, 68: 523-533. https://doi.org/10.1016/j.jmapro.2021.05.069 P. Jin, Y. B. Liu, Q. J. Sun. Evolution of crystallographic orientation, columnar to equiaxed transformation and mechanical properties realized by adding TiCps in wire and arc additive manufacturing 2219 aluminum alloy. Additive Manufacturing, 2021, 39: 101878. https://doi.org/10.1016/j.addma.2021.101878 A. K. Sinha, K. P. Yagati. Wire Arc Additive Manufacturing of Al-Cu Alloy-Grain Refinement, Strengthening and Thermal Simulation. Silicon, 2024, 16: 441-461. https://doi.org/10.1007/s12633-023-02667-1 J. H. Martin, B. D. Yahata, J. M. Hundley. 3D printing of high-strength aluminium alloys. Nature, 2017, 549: 365-369. https://doi.org/10.1038/nature23894 H. S. Ren, Y. B. Liu, H. Y. Kong, C. Y. Song, Y. F. Xie, Q. J. Sun. Microsture and mechanical properties of Al-Cu alloy during wire and arc additive manufacturing by adding micron TiB 2 particles. Virtual and Physical Prototyping, 2024, 19(1): 1-18. https://doi.org/10.1080/17452759.2024.2351170 Y. N. Hu, F. R. CHEN, S. L. Cao, Y. F. Fan, R. J. Xie. Improvement of microstructure and mechanical properties of CMT wire arc additive manufacturing Al-Si alloy deosition via interlayer coating TiC nanoparticles. Materials Today Communications, 2024, 38: 107851. https://doi.org/10.1016/j.mtcomm.2023.107851 T. Klein, A. Arnoldet, R. Lahnsteiner, M. Schnall. Microstructure and mechanical properties of a structurally refined Al–Mg–Si alloy for wire-arc additive manufacturing. Materials Science and Engineering: A, 2022, 830: 142318. https://doi.org/10.1016/j.msea.2021.142318 H. Su, W. Gao, Z. H. Feng, Z. Lu. Processing microstructure and tensile properties of nano-sized Al 2 O 3 particle reinforced aluminum matrix composites. Materials and Design, 2016, 36: 590-596. https://doi.org/10.1016/j.matdes.2011.11.064 N. Mclean. M. J. Bermingham, P. Colgrove, A. Sales, M. S. Dargusch. Understanding the grain refinement mechanisms in aluminium 2319 alloy produced by wire arc additive manufacturing. Science and technology of welding and joining, 2022, 27(6): 479-489. https://doi.org/10.1080/13621718.2022.2064704 J. X. Sun, H. S. Yu, D. X. Zeng, P. Shen. Wire-powder-arc additive manufacturing: A viable strategy to fabricate carbide cermics/aluminum alloy multi-material structures. Additive Manufacturing, 2022, 51: 102637. https://doi.org/10.1016/j.addma.2022.102637 X. P. Song, J. K. Niu, J. K. Huang, D. Fan, S. R. Yu, Y. J. Ma, et al. The Effect of B 4 C Powder on Properties of the WAAM 2319 Al Alloy. Materials, 2023, 436(16): 1-14. https://doi.org/10.3390/ma16010436 M. Sokoluk, C. Z. Cao, S. H. Pan, X. C. Li. Nanoparticle-enabled phase control for arc welding of unweldable aluminum alloy 7075. Nature communications, 2019, 98(10): 1-8. https://doi.org/10.1038/s41467-018-07989-y W. Q. Liu, C. Z. Cao, J. Q. Xu, X. J. Wang, X. C. Li. Molten salt assisted solidification nanoprocessing of Al-TiC nanocomposites. Materials Letters, 2016, 18: 392-395. https://doi.org/10.1016/j.matlet.2016.09.023 G. Langelandsvik, M. Eriksson, O. M. Akselsen, H. J. Roven. Wire arc additive manufacturing of AA5183 with TiC nanoparticles. The International Journal of Advanced Manufacturing Technology, 2022, 119: 1047-1058. https://doi.org/10.1007/s00170-021-08287-6 D. Oropeza, D. C. Hofmann, K. Williams, S. Firdosy, P. Bordeenithikasem, M. Sokoluk, et al. Welding and additive manufacturing with nanoparticle-enhanced aluminum 7075 wire. Journal of Alloys and Compounds, 2020, 834: 154987. https://doi.org/10.1016/j.jallcom.2020.154987 Q. Y. Liu, H. B. Mi, L. Y. Feng, W. Guo, B. Y. He. A critical overview of welding and directed energy deposition with flux-cored wires. Journal of Manufacturing Porcesses, 2025, 142: 231-268. https://doi.org/10.1016/j.jmapro.2025.03.097 V. P. Lyalyakin, D. B. Slinko, V. A. Denisov. Preparation of Composite Coatings by Electric Arc Spraying Using Flux-Cored Wires. Russian Metallurgy, 2022, 13: 1753-1739. https://doi.org/10.1134/S0036029522130183 Y. J. Zhou, S. M. Yin, Y. Jiang, Q. L. Zhou, J. B. Peng, Y. W. Yan. Wire and arc additive manufacturing fabrication of ODS-RAFM steels and preliminary evaluation on microstructures and mechanical properties. Journal of Nuclear Materials, 2022, 572: 154068. https://doi.org/10.1016/j.jnucmat.2022.154068 N. H. Xiao, J.Y. Liu. Cold bending forming technique. First Edition.Chemical Industry Press，2008. J. F. Leng, Y. F. Dong, B. H. Ren, X. L. Xu, B. Zhu, S. Tian. Effect of Rolling Deformation on Microstructure and Properties of 7085 Aluminum Alloy. Physics of Metals and Metallography, 2021, 122: 1543-1550. https://doi.org/10.1134/S0031918X21140131 S. C. Yang, Y. B. Chen. Modern advanced engine technology. Design and Manufacture of Diesel Engine, 2001, 1: 8-14. https://doi.org/10.3969/j.issn.1671-0614.2001.01.002 G. H. Wu, K. Q. Lv. Mathematical analysis of stability of powder filling rate of flux-cored wire. Welding Technology, 2011, 40(9): 32-34. https://doi.org/10.1134/S0031918X21140131 GB/T 310557.3. Granular materials-Physical properties-Part 3: Fluidity index, 2018 Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 24 Jun, 2025 Reviewers invited by journal 24 Jun, 2025 Editor invited by journal 29 May, 2025 Editor assigned by journal 22 May, 2025 First submitted to journal 19 May, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6699297","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":475788031,"identity":"023c0c8d-ea0b-4130-8684-e6e0cba41042","order_by":0,"name":"Bo Zheng","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Bo","middleName":"","lastName":"Zheng","suffix":""},{"id":475788032,"identity":"7a9f34b1-dc9f-4125-942b-48ca6e52a041","order_by":1,"name":"Shengfu Yu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYBACgxvpz0A0PwMzY+ODhAobYrTkmIFoyQZ25maDB2fSCGuRnJHDBtHCz94m+bDtEGEt/BI5bA8+7qiVMDjM2FaRwHaAgb+9OwGvFjaJ9OeGM88cB2u5kcBzh0HizNkNBLQkmEnzth2rg2iReMZgIJFLhJa/bcfAthQkGBwmUgtjWw1YC0NCAjFaeM6YSfa2HZCQPMzYLJFwII2HsF/Y259J/Gyrk+A7f/zhx5//bOT423vxa4GCw3AWDzHKQaCOWIWjYBSMglEwEgEA01VLoPXzJQMAAAAASUVORK5CYII=","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":true,"prefix":"","firstName":"Shengfu","middleName":"","lastName":"Yu","suffix":""},{"id":475788033,"identity":"28de117b-924e-4b5a-95ae-0ce8187df40c","order_by":2,"name":"Zhengyu Yu","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Zhengyu","middleName":"","lastName":"Yu","suffix":""},{"id":475788034,"identity":"db20d10a-c25f-4651-a55f-49ea04b13dac","order_by":3,"name":"Lun Tang","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Lun","middleName":"","lastName":"Tang","suffix":""}],"badges":[],"createdAt":"2025-05-19 13:10:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6699297/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6699297/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85542380,"identity":"d2b1bbd3-3f31-4390-bf54-4f91d8ca2229","added_by":"auto","created_at":"2025-06-27 07:08:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":215965,"visible":true,"origin":"","legend":"\u003cp\u003ePreparation process of flux-cored wire: (a) Rolling and forming, (b) Drawing and reducing diameter\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/a36035270c184f090d66a356.png"},{"id":85542479,"identity":"35ac29db-6ca2-43f8-9d2f-f7a399adf170","added_by":"auto","created_at":"2025-06-27 07:08:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":142429,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of roll rolling: (a) G1-G3 forming rolls, (b) G4-G6 sealing rolls\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/35fb384f24ef4b1d48027adc.png"},{"id":85542393,"identity":"7347a804-e839-4aab-bf44-217201f3d0d4","added_by":"auto","created_at":"2025-06-27 07:08:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":487943,"visible":true,"origin":"","legend":"\u003cp\u003eFinite element meshing of forming roll rolling and aluminum strip forming\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/0a0c26b75375a8c3fb7bb229.png"},{"id":85542398,"identity":"e5c0d8ef-12ad-4a0f-9cd9-1ce0b28acbf7","added_by":"auto","created_at":"2025-06-27 07:08:31","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":141145,"visible":true,"origin":"","legend":"\u003cp\u003eSize design, object and reducing diameter of drawing die\u003c/p\u003e","description":"","filename":"image4.tiff.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/e89c4e907d0fcc92f21797f5.jpg"},{"id":85542387,"identity":"8eddadcc-acc7-4072-8ead-5f4cf1a61a36","added_by":"auto","created_at":"2025-06-27 07:08:31","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":182928,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of equivalent stress in drawing process\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/7c9a7a789e286c5c9072d9c0.png"},{"id":85542426,"identity":"a99b1064-237d-4401-ab21-3c01eb8b14f9","added_by":"auto","created_at":"2025-06-27 07:08:32","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":275755,"visible":true,"origin":"","legend":"\u003cp\u003eProduction demonstration line of aluminum alloy flux-cored wire\u003c/p\u003e","description":"","filename":"image6.tiff.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/07e07222dabf3a1dfc0ea739.jpg"},{"id":85542430,"identity":"e700ac67-22fa-4526-9d47-daa0789d7230","added_by":"auto","created_at":"2025-06-27 07:08:32","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":151840,"visible":true,"origin":"","legend":"\u003cp\u003eMetallography of aluminum strips annealed at different temperatures: (a) Initial state, (b) 230℃, (c) 270℃, (d) 310℃\u003c/p\u003e","description":"","filename":"image7.tiff.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/21e6939c26487c3026a9d9eb.jpg"},{"id":85542406,"identity":"94812bf2-5304-4c7d-bfee-299bc75046bd","added_by":"auto","created_at":"2025-06-27 07:08:32","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":280572,"visible":true,"origin":"","legend":"\u003cp\u003eReverse pole figure, grain size distribution and pole figure: (a)-(c) initial state, (d)-(f) annealing temperatures 230 ℃\u003c/p\u003e","description":"","filename":"image8.tiff.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/47e56bb0402c5925dd47e561.jpg"},{"id":85542478,"identity":"1b0cb67e-cfd1-4d27-9767-34206b4abee5","added_by":"auto","created_at":"2025-06-27 07:08:34","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":354675,"visible":true,"origin":"","legend":"\u003cp\u003eAluminum strip mechanical properties: (a) Stress-strain curve, (b) Tensile histogram. Fracture morphology: (c) Initial state, (d) 230℃\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/29a2923ee3e1b829b7f761c1.png"},{"id":85543421,"identity":"e258401f-d0e5-4bf7-9c6b-1e38df9b469e","added_by":"auto","created_at":"2025-06-27 07:24:32","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":1034582,"visible":true,"origin":"","legend":"\u003cp\u003eFlowability simulation of powder cores with different particle sizes during drawing\u003c/p\u003e","description":"","filename":"image10.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/efc7dd7d0575ce4b20779a8a.png"},{"id":85542425,"identity":"70d72cef-814a-4c69-afca-85da2cadae85","added_by":"auto","created_at":"2025-06-27 07:08:32","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":393052,"visible":true,"origin":"","legend":"\u003cp\u003eFlowability test process of core powder\u003c/p\u003e","description":"","filename":"image11.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/f696f83e806b9e72edaee607.png"},{"id":85542861,"identity":"ff536cbe-c4b4-4df6-b264-5b9676bab734","added_by":"auto","created_at":"2025-06-27 07:16:32","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":602471,"visible":true,"origin":"","legend":"\u003cp\u003eIn-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e flux-cored wire prepared\u003c/p\u003e","description":"","filename":"image12.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/a327f4937448f680378c63a3.png"},{"id":85543422,"identity":"006de432-ecdf-4a45-9078-8420a6176aae","added_by":"auto","created_at":"2025-06-27 07:24:33","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":271551,"visible":true,"origin":"","legend":"\u003cp\u003eScanning electron microscopy observation of wire morphology: (a)-(b) ceramic aluminum alloy flux-cored wire, (c)-(d) commercial aluminum alloy solid wire\u003c/p\u003e","description":"","filename":"image13.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/43835d32b3b168f45c155c5e.png"},{"id":85542423,"identity":"c3ba338e-fbf9-493b-9d92-5705ca41fc27","added_by":"auto","created_at":"2025-06-27 07:08:32","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":276214,"visible":true,"origin":"","legend":"\u003cp\u003e(a)The morphology of the deposited members and (b) the surface contour curve\u003c/p\u003e","description":"","filename":"image14.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/0146c56bb87a9d576c9863a4.png"},{"id":85542867,"identity":"849f7e84-3c10-4706-8f83-51a010f692b0","added_by":"auto","created_at":"2025-06-27 07:16:33","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":211742,"visible":true,"origin":"","legend":"\u003cp\u003eDroplet transition and arc morphology of flux-cored wire\u003c/p\u003e","description":"","filename":"image15.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/16b4d1454eb92c8a7ea5e7a3.png"},{"id":85542412,"identity":"0cfbb1cd-9b91-480c-a81d-d14a674b549a","added_by":"auto","created_at":"2025-06-27 07:08:32","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":28292,"visible":true,"origin":"","legend":"\u003cp\u003eCurrent-voltage profiles of WAAM rod process\u003c/p\u003e","description":"","filename":"image16.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/fdd8bfde8c97c0d23a09bcd0.png"},{"id":85542444,"identity":"adeb4bb8-cc99-4342-8a35-e77610cfd33b","added_by":"auto","created_at":"2025-06-27 07:08:33","extension":"jpg","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":193127,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructure of cored wire deposited metal: (a) metallography, (b) scanning electron microscopy, (c) transmission electron microscopy, (d) energy spectrum of particles\u003c/p\u003e","description":"","filename":"image17.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/f09ec1450ca2a924b3629ebb.jpg"},{"id":85542862,"identity":"37d50a2a-aa4c-47da-ae3f-1fd96213edbd","added_by":"auto","created_at":"2025-06-27 07:16:32","extension":"png","order_by":18,"title":"Figure 18","display":"","copyAsset":false,"role":"figure","size":562215,"visible":true,"origin":"","legend":"\u003cp\u003eAircraft outer skin: (a) model, (b) Object\u003c/p\u003e","description":"","filename":"image18.png","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/d71efb7a49a244d0b3faa152.png"},{"id":85543424,"identity":"0aeb28c4-7e91-4a0b-b26c-e0f0172f4b8b","added_by":"auto","created_at":"2025-06-27 07:24:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8032469,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6699297/v1/2d89a18d-a9ec-4d3a-a175-da68814106ce.pdf"}],"financialInterests":"","formattedTitle":"The preparation method and application of aluminum alloy flux-cored wire for wire arc additive manufacturing","fulltext":[{"header":"0 Introduction","content":"\u003cp\u003eAluminum alloy has become a critical material for lightweight design in aerospace, rail transit, and related industries, due to its exceptional specific strength, corrosion resistance, and excellent machinability [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Wire arc additive manufacturing (WAAM) has emerged as a key technique for fabricating large aluminum alloy components, primarily owing to its high deposition rate, high material utilization, and relatively low equipment costs [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. However, aluminum alloy components produced using conventional WAAM processes often exhibit inherent limitations, such as coarse grain structures and elevated porosity levels, which can significantly degrade the mechanical properties of the deposited metal. These limitations present a major obstacle to the broader application of WAAM-fabricated aluminum alloys component in engineering [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Consequently, improving the mechanical properties of aluminum alloy deposited metal through WAAM remains a critical technical challenge.\u003c/p\u003e \u003cp\u003eResearchers have developed various techniques to enhance the mechanical properties of aluminum alloy deposited metal produced by WAAM. Key methods include interlayer rolling [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], interlayer hammering [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], interlayer rotary friction [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], and interlayer friction stir processing [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Interlayer rolling, as demonstrated by Colegrove et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and Gu et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], significantly refines the primary coarse-grained structure, achieving grain refinement, pore closure, and size reduction. Similarly, Fang et al. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] proposed an interlayer hammering-assisted WAAM method for aluminum alloys, which increased dislocation density and improved tensile strength by 16% compared to as-deposited metal. These findings underscore the potential of plastic deformation techniques in enhancing the mechanical properties of aluminum alloy components. However, these methods require substantial downward forces on the deposited metal, necessitating equipment modifications and incurring high costs. Furthermore, the significant downward hammering forces impose severe process constraints, particularly for delicate thin-walled structures. Despite these challenges, the techniques offer promising avenues for improving the performance of aluminum alloy components in WAAM processes.\u003c/p\u003e \u003cp\u003eCeramic particle-reinforced aluminum alloy WAAM technology has garnered considerable attention due to its strong process compatibility and cost controllability [\u003cspan additionalcitationids=\"CR16 CR17 CR18 CR19 CR20 CR21 CR22 CR23\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Jin et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] specifically incorporated 5 \u0026micro;m TiC particles during WAAM 2219 aluminum alloy. Their findings showed that TiC effectively prevented the segregation of Cu at grain boundaries, improved the interface compatibility between the matrix and θ'-Al\u003csub\u003e2\u003c/sub\u003eCu, and reduced the system\u0026rsquo;s nucleation free energy. As a result, the grain size was refined to 18.4 \u0026micro;m, and columnar crystal formation was eliminated. Sinha et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] introduced SiC particles into the interlayer during WAAM aluminum alloy, finding that the addition of SiC promoted the formation of equiaxed grains throughout the sample. This approach resulted in an improvement of 48 MPa in mechanical properties compared to direct deposition. Martin et al. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] used nano-ZrO\u003csub\u003e2\u003c/sub\u003e ceramic particles as the reinforcing phase, observing a notable grain refinement effect. Similarly, Ren et al. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] found that TiB\u003csub\u003e2\u003c/sub\u003e particles significantly refined the coarse grains in 2319 aluminum alloy produced by WAAM, suppressed Cu segregation at grain boundaries, and improved microstructural uniformity, thereby enhancing the mechanical properties of the deposited metal. These findings collectively demonstrate that ceramic particle reinforcement is an effective approach to improving the performance of aluminum alloy components fabricated via WAAM. However, the realization of the above method is mainly to introduce ceramic particle reinforced phase by interlayer coating method, which is difficult to accurately control the content of ceramic phase introduced into the WAAM process, and the coating method makes the manufacturing efficiency low.\u003c/p\u003e \u003cp\u003eTo overcome the limitations of conventional coating techniques, Sun et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] developed a wire-powder WAAM system. This system incorporates an independent axial powder feeder that enables precise control over both the type and content of ceramic particles (SiC, B\u003csub\u003e4\u003c/sub\u003eC, TiC, WC) introduced during the process. In a similar approach, Song et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] demonstrated the incorporation of B\u003csub\u003e4\u003c/sub\u003eC ceramics into 2319 aluminum alloy deposits metal through side-axis powder feeding in WAAM. While these methods achieve accurate control over ceramic particle quantities, they suffer from inherent drawbacks including powder trajectory divergence, susceptibility to airflow interference, and low powder utilization efficiency. In an alternative approach addressing these limitations, Sokoluk et al. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] fabricated a novel 7075 aluminum alloy solid wire incorporating TiC\u003csub\u003enp\u003c/sub\u003e. Their methodology involved preparing composite materials comprising Zn, Cu, Mg, Cr, and TiC nanoparticles, followed by casting these composites into square ingots and producing 3.17 mm diameter wires through hot extrusion. Similarly, Liu, Langelandsvik, and Oropeza et al. [\u003cspan additionalcitationids=\"CR29\" citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] successfully fabricated aluminum alloy solid wires incorporating TiC\u003csub\u003enp\u003c/sub\u003e using the aforementioned process. This method offers significant advantages, including precise control over ceramic content and the elimination of the need for a side-axis wire feeding device. It should be emphasized that while this approach enables precise control of ceramic content and eliminates the need for a side-axis wire-feeding device. It presents notable drawbacks. The initial stages of wire preparation are highly intricate, and the associated costs incurred during trial-and-error iterations are substantial. It can be seen that how to realize the precise introduction of ceramic is an important technical problem, and it is urgent to develop a new method for the introduction of ceramic particles.\u003c/p\u003e \u003cp\u003eFlux-cored wire involves wrapping ceramic particle powder with a metal strip [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The key advantage of this technology is its ability to simultaneously and accurately transport the strengthening element and matrix metal using wire as the base material. Significant advancements have been made in carbon steel flux-cored wire technology. Lyalyakin et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] demonstrated the use of a 0.5 mm thick ST2 steel strip for producing high-carbon cored wire. Zhou et al. [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e] utilized Fe-Cr steel strips with a 15% fill rate to fabricate high-chromium cored wire. Currently, most cored powder for WAAM are made of carbon steel. Few studies have been conducted on aluminum alloy flux-cored wire. Different from carbon steel flux-cored wire production, the preparation of ceramic aluminum alloy cored wires presents numerous challenges. For example, aluminum strips have low elongation and are prone to work hardening during drawing, making the wire prone to breakage. Additionally, the flux core powder in these wires has low fluidity and tends to agglomerate, further contributing to wire breakage. Therefore, it is essential to develop specialized preparation methods and devices for ceramic aluminum alloy flux-cored wire.\u003c/p\u003e \u003cp\u003eIn this paper, the aluminum strip method is employed to prepare special ceramic aluminum alloy flux-cored wire for WAAM. First, a mold, process, and device for aluminum alloy flux-cored wire preparation were developed. Then, the heat treatment process of aluminum strip was investigated. Finally, using an in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire for WAAM as an example, the composition of the flux-cored wire was designed. Development experiments were conducted, and the forming, microstructure, and mechanical properties of the deposited metal were evaluated. These findings provide a process and theoretical foundation for the development of WAAM flux-cored wire.\u003c/p\u003e"},{"header":"1 Aluminum-based flux-cored wire drawing preparation system","content":"\u003cp\u003eThe Aluminum-based flux-cored wire is prepared through a process involving an aluminum strip of specific thickness and width coated with core powder. This process consists of four main stages: raw material preparation, wire forming, drawing, and coiling. Raw material preparation involves several key steps, including aluminum strip cleaning, particle powder screening, drying, and flow ability testing. The wire forming stage specifically includes the roll forming of the aluminum strip. The detailed preparation process is as follows: the forming roller first shapes the aluminum strip into a U-profile. Subsequently, the conveyor belt drives the powder into the U-shaped aluminum strip. Finally, the sealing roller closes and overlaps the U-shaped strip into an O-shape, resulting in the large-diameter cored wire, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea. The drawing stage comprises multiple sequential processes. Through the coordinated action of multiple sets of drawing dies, the aluminum-based cored wire undergoes dimensional reduction until it reaches the target diameter, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb. In the final coiling stage, a winding machine and packaging machine are employed to wind and package the wire, producing the finished product. Notably, both the roll forming unit and the drawing reduction unit play crucial roles in the preparation of aluminum-based flux-cored wire.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e1.1 Roll unit design\u003c/h2\u003e \u003cp\u003eThe roll unit includes a forming roll and a sealing roll. The forming roller is used to roll the aluminum strip into a U-shaped to ensure that the powder feeding unit of the subsequent conveyor belt can fully fill the powder into the U-shaped groove. The sealing roller is used to close the U-shaped aluminum strip into a lapped O-type to prevent the powder core from leaking. The aluminum strip is plastically deformed under the action of the punch/die of the upper and lower rollers. The number and size of the rollers have an important influence on the rolling forming of the aluminum strip. The number of rollers significantly influences the trade-off between cost efficiency and material properties during aluminum strip processing. Utilizing fewer rollers reduces production costs and enhances processing efficiency. However, this approach results in excessive single-stage deformation of the aluminum strip, leading to elevated internal stresses that may compromise subsequent drawing reduction operations. Conversely, increasing the number of roller groups diminishes the internal stress levels in the aluminum strip, but at the expense of higher production costs and reduced operational efficiency. Therefore, it is necessary to design the roll unit.\u003c/p\u003e \u003cp\u003eThe aluminum strip employed in this study is 1060 pure aluminum, with a thickness of 0.8 mm and a width of 12 mm. The diameter of the cored wire after forming roll process is designed to be 3.8 mm, and the total elongation coefficient, denoted as L\u003csub\u003eY\u003c/sub\u003e (The ratio of the cross-sectional area of the finished cored wire to the initial aluminum strip), is 1.67. The forming process is carried out using three groups of forming rollers, each consisting of an upper and lower roller. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea. The G1 forming roller transforms the flat 1060 aluminum strip into a slightly curved concave shape. Subsequently, the G2 forming roller further bends the concave strip into one with a larger curvature. Finally, the G3 forming roller bends the concave strip with a large bending angle to achieve the desired U-shape. The closing process is performed using three groups of sealing rolls, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb. The G4 sealing roller initially closes the U-shaped aluminum strip. The G5 sealing roller is then used to bend the sides of the partially closed strip, and the G6 sealing roller completes the process by forming the fully lapped O-shaped wire. According to the relationship between the total elongation coefficient (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e\u003cem\u003eY\u003c/em\u003e\u003c/sub\u003e) and the average elongation coefficient (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e\u003cem\u003eJ\u003c/em\u003e\u003c/sub\u003e) of each pass, as defined in Eq.\u0026nbsp;(\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The value of L\u003csub\u003eJ\u003c/sub\u003e is calculated to be 1.09.\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{L}_{J}=\\sqrt[N]{{L}_{Y}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cem\u003eN\u003c/em\u003e represents the number of passes rolled by the roll, which is 6 here.\u003c/p\u003e \u003cp\u003eIn adherence to the principle of \"Small at both ends and large in the middle\", the process is designed to ensure the stability of the initial rolling stage of the aluminum strip and the accuracy of the final rolling stage. The elongation coefficients for the first (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e) and sixth (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e) passes are reduced by 20% compared to the average elongation coefficient, as calculated by Eq.\u0026nbsp;(\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The elongation coefficients for passes two to five (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e to \u003cem\u003eL\u003c/em\u003e\u003csub\u003e5\u003c/sub\u003e) are determined using Eq.\u0026nbsp;(\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The calculated elongation coefficients for each pass, from \u003cem\u003eL\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e to \u003cem\u003eL\u003c/em\u003e\u003csub\u003e6\u003c/sub\u003e, are as follows: 1.072, 1.12, 1.12, 1.12, 1.12, and 1.072, respectively.\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:{L}_{\\left(\\text{1,6}\\right)}=1+0.8({L}_{J}-1)$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\:{L}_{(2-5)}=\\sqrt[4]{\\frac{{L}_{Y}}{{L}_{1}\\ast\\:{L}_{6}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo evaluate the rolling validity of the designed roll, a simulation using finite element software, with the G1 forming roller as an example. The simulation involved a static universal module, where the upper and lower rollers were modeled as rigid bodies. Friction contact was employed to reduce computational workload, with a friction coefficient of 0.15. The aluminum strip was represented as a flexible body with a hexahedral mesh, ensuring accurate deformation analysis. The quadrilateral main grids were used to discretize the upper and lower rolls, enhancing the simulation's precision. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the simulation results demonstrate that the designed G1 forming roller induces significant plastic deformation on the aluminum strip's surface, achieving good forming quality with flat edges. These findings confirm the practicality of the designed forming roller. Furthermore, the reliability of the design method underscores its applicability for the design and preparation of forming rollers. This approach not only validates the effectiveness of the current design but also provides a robust framework for future applications in roller design.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003e1.2 Drawing die design\u003c/h3\u003e\n\u003cp\u003eThe drawing die was categorized into 12 distinct groups, each with a die aperture diameter of 3.2 mm, 2.84 mm, 2.52 mm, 2.24 mm, 1.99 mm, 1.81 mm, 1.66 mm, 1.53 mm, 1.42 mm, 1.32 mm, 1.24 mm, and 1.17 mm, respectively. The drawing compression ratio, defined as the ratio of the difference between the cross-sectional area of the inlet and outlet to the cross-sectional area of the inlet, was maintained at 21% for the first seven passes and progressively reduced to 17%, 16%, 15%, 14%, 14%, 12%, and 11% for the subsequent passes. Notably, the total compression ratio was meticulously controlled 20% and rationally distributed across each individual drawing process. This controlled approach effectively prevents wire fracture caused by excessive deformation, ensuring a stable and reliable wire drawing operation.\u003c/p\u003e \u003cp\u003eThe drawing die consists of four main areas: the lubrication area, the compression area, the sizing area, and the outlet area, with a total length (L) of 12 mm. The lubrication area facilitates the entry of lubricant into the mold hole, thereby reducing drawing resistance. The feed cone angle (θ\u003csub\u003e1\u003c/sub\u003e) in the lubrication area ranges between 80\u0026deg; and 100\u0026deg;, with a recommended value of 90\u0026deg; based the research of Leng [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The length (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e) is calculated as 1.3 times the feed diameter (\u003cem\u003eD\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e), determined by the specific mold used in this study. The compression area induces forced extrusion deformation in the aluminum wire. Its length (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e) is calculated as \u003cem\u003eL\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eL\u003c/em\u003e-\u003cem\u003eL\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e-\u003cem\u003eL\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e-\u003cem\u003eL\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e. The cone angle (\u003cem\u003eθ\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e) in the compression area ranges from 20\u0026deg; to 28\u0026deg;. Given that the final product is a thin wire of 1.2 mm, a cone angle of 20\u0026deg; is preferred for the small-angle compression area. The sizing area stabilizes the diameter of the aluminum wire and corrects any unevenness. Its length (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e) is 0.3 times the total length (\u003cem\u003eL\u003c/em\u003e). The outlet area is designed to prevent scratches during the removal of the aluminum wire from the mold. The exit cone angle (\u003cem\u003eθ\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e) ranges from 60\u0026deg; to 90\u0026deg;, with a selected value of 75\u0026deg;. The length (\u003cem\u003eL\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e) is 1.3 times the feed diameter (\u003cem\u003eD\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e). Based on the aforementioned analysis and calculation formulas, the key dimensions of each drawing die can be determined. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e illustrates the drawing die used for a wire diameter of 1.81 mm.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea-d presents simulated equivalent stress distribution maps for wires drawn through dies with different aperture diameter (2.25 mm, 1.81 mm, 1.42 mm, and 1.17 mm). The analysis reveals a clear correlation between die aperture diameter size and maximum tensile stress. As die aperture diameter decreases from 2.25 mm to 1.17 mm, corresponding maximum stresses decrease progressively from 14.8 MPa to 7.23 MPa, respectively. The spatial distribution analysis demonstrates two critical findings. First, across all simulations, maximum stresses consistently concentrate in central regions exhibiting irregular radial patterns. Second,the simulation results confirm absence of wire fracture incidents, indicating theoretical reliability in die design. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee shows the stress contour map of 1.17 mm diameter wire drawing process. It can be seen that the stress during the drawing process is mainly concentrated in the left area of the wire transversely close to the left side. The maximum stress area is the central area of the wire transverse (Blue area), rather than the transition area from large diameter to small diameter. This shows that the tube wall (Aluminum strip) of the wire is not the maximum stress during the drawing process. Therefore, the die is expected to ensure that the wire is not broken during drawing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn summary, the roll is designed and fabricated based on the extension coefficient of each rolling pass and the shape of the roll groove. The roll is made of cemented carbide, which possesses significantly higher strength and stiffness compared to the aluminum strip. The equipment units required for each stage are integrated into a cohesive system, and a production demonstration line for the preparation of aluminum alloy flux-cored wire has been established, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"2 Aluminum strip preheating treatment process","content":"\u003cp\u003eThe rolled aluminum strip is prone to work hardening during the drawing process. The aluminum strip requires annealing before cored wire fabrication to enhance ductility and plasticity, preventing fractures during drawing. According to the standard GJB 1694A-2019 heat treatment requirements of wrought aluminum alloy, the annealing process of aluminum strip was optimized by orthogonal experiment method, and the heat treatment environment was vacuum atmosphere. L9(3\u003csup\u003e3\u003c/sup\u003e) was selected to design the experimental scheme, and the three factors of the experiment were determined as follows: heating temperature \u003cem\u003eA\u003c/em\u003e for 230℃, 270℃ and 310℃, holding time \u003cem\u003eB\u003c/em\u003e fro 90 min, 120 min and 150 min, cooling method \u003cem\u003eC\u003c/em\u003e (Three levels were air cooling, water cooling and water cooling (Quasi-level)). The response target is the elongation of the aluminum strip.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents the experimental design and corresponding results. Using the elongation of the aluminum strip as the response variable, a range analysis was conducted following orthogonal test methodology. The results of this analysis are listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, where \u003cem\u003eK\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e-\u003cem\u003eK\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e represent the average elongation values for each factor at three levels, and \u003cem\u003eR\u003c/em\u003e denotes the difference between \u003cem\u003eK\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e and \u003cem\u003eK\u003c/em\u003e\u003csub\u003emin\u003c/sub\u003e. A larger \u003cem\u003eR\u003c/em\u003e value indicates a stronger influence of that factor on elongation. The analysis reveals that heating temperature has the greatest effect on elongation, followed by holding time, while cooling method (Factor \u003cem\u003eC\u003c/em\u003e) exhibits the smallest \u003cem\u003eR\u003c/em\u003e value and thus minimal influence. Additionally, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e identifies the optimal process parameters as \u003cem\u003eA\u003c/em\u003e1\u003cem\u003eB\u003c/em\u003e2\u003cem\u003eC\u003c/em\u003e1, corresponding to a heating temperature of 230℃, holding time of 120 min, and air cooling. Under these conditions, the annealed aluminum strip achieves its highest elongation.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eOrthogonal test scheme and results of heat treatment of aluminum strips\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHeating temperature \u003cem\u003eA\u003c/em\u003e/℃\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHolding time\u003c/p\u003e \u003cp\u003e\u003cem\u003eB\u003c/em\u003e/min\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCooling method \u003cem\u003eC\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eElongation\u003c/p\u003e \u003cp\u003e\u003cem\u003eD\u003c/em\u003e/%\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAir cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWater cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWater cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e21.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e270\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWater cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e270\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWater cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e270\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAir cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e18.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e310\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWater cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e310\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e120\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAir cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e19.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e310\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWater cooling\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e59.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e51.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e52.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e48.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFactor sequence\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eA\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eB\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;\u003cem\u003eC\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOptimized compose\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eA\u003c/em\u003e1\u003cem\u003eB\u003c/em\u003e2\u003cem\u003eC\u003c/em\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows the metallographic diagrams of aluminum strip at holding times of 120 min under air cooling conditions, with annealing temperatures of 230℃, 270℃, and 310℃, respectively. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea, the initial rolled aluminum strip exhibits elongated fibrous grains that grow along the rolling direction, indicating a typical rolling deformation structure. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb, under annealing at 230℃, the fibrous deformed structure is replaced by an equiaxed recrystallized structure. This is due to the high density of dislocation defects in the rolled aluminum strip [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. After annealing treatment, the material first undergoes the recovery stage, where vacancy density decreases, and with prolonged holding time, it enters the recrystallization stage. During this process, internal dislocations rearrange and induce nucleation, resulting in regular and uniformly sized grains. As shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec and d, when the annealing temperature increases from 230℃ to 310℃, the grain shape becomes more uniform with higher heating temperatures. However, significant grain coarsening occurs, and grain size gradually increases, which is particularly evident at an annealing temperature of 310℃.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe optimal annealing parameters from Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e are used to anneal the aluminum strip. Figures\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea-f show the reverse pole figure, grain size distribution, and pole figure of the annealed aluminum strip. These images were obtained using a scanning electron microscope equipped with electron backscatter diffraction. Compared to the initial aluminum strip (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea), the internal grains change from fibrous to equiaxed, and grain size increases from 13 \u0026micro;m (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb) to 33 \u0026micro;m, as shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ed and e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ec, the initial aluminum strip exhibits a strong texture along the deposition direction (Y0) on the low-index crystal plane (100). The maximum pole density is 17.58, causing fibrous columnar crystals to form along the rolling direction. After annealing at 230℃, the fibrous columnar crystals transform into equiaxed crystals. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ef, the maximum pole density on the (100) plane decreases to 16.56, indicating inhibited directional growth of fibrous columnar crystals and promoting equiaxed grain formation. It can be seen that recovery and recrystallization reduce dislocation density within the aluminum strip, leading to decreased tensile strength and increased plasticity and elongation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ea and b show the stress-strain curves and mechanical properties histograms of the initial aluminum strip and the aluminum strip annealed at 230℃ for 120 min. The initial aluminum strip has a tensile strength of 114 MPa and an elongation of 4.8%. After annealing at 230℃, the tensile strength decreases to 67 MPa, while the elongation increases to 22.3%. Figure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ec illustrates the fracture morphology of the tensile specimen of the initial aluminum strip. A small number of elliptical dimples are visible on the fracture surface. These dimples are large in size and depth, with a uniform distribution. After annealing at 230℃, the tensile necking of the aluminum strip increases, and the fracture morphology becomes honeycomb-shaped. Additionally, the number of elliptical dimples on the surface significantly increases, with a very uniform distribution, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ed. Plastic deformation white tearing ridges form between the dimples, and the ductile fracture phenomenon is more pronounced. This improvement in ductility is due to the annealing treatment, which changes the grain structure from fibrous to equiaxed with uniform grain size.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn summary, prior to the preparation of the ceramic aluminum alloy flux-cored wire, the aluminum strip undergoes annealing to ensure it achieves high elongation and tensile strength. The annealing process is carried out under the following optimized parameters: a heating temperature of 230℃, a holding time of 120 min, and an optimized cooling method involving air cooling.\u003c/p\u003e"},{"header":"3 The fluidity of the core powder","content":"\u003cp\u003eThe flowability of core powder plays a critical role in the preparation of aluminum alloy flux-cored wires. Figure\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e illustrates the powder flow behavior as a 1.99 mm-diameter wire passes through a drawing die with an aperture diameter size of 1.81 mm. The analysis reveals that the maximum flow velocity of the core powder varies significantly with particle size: 0.0943 m/s for 80 \u0026micro;m, 0.102 m/s for 150 \u0026micro;m, 0.104 m/s for 200 \u0026micro;m, and 0.111 m/s for 300 \u0026micro;m. These results demonstrate a clear positive correlation between particle size and flowability\u0026mdash;larger particles exhibit progressively higher flow velocities, suggesting enhanced powder mobility with increasing granule dimensions. Analysis of flow visualization further reveals distinct spatial variations in powder flow behavior. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e, the core powder exhibits higher flow velocity in the central region of the wire compared to areas adjacent to the outer wall. This phenomenon, consistent with findings reported by Yang et al. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e], arises from viscous resistance between powder particles and the pipe wall. Based on theoretical considerations, during the drawing process of the flux-cored wire, an excessively small powder particle size may reduce the overall fluidity of the core powder, particularly near the wire wall. This reduction in local powder fluidity can lead to increased frictional forces between the powder particles and the wire wall, resulting in increased loads on the aluminum strip. Consequently, this raises the fracture tendency during the drawing process and may ultimately lead to wire failure. Clearly, the particle size of the core powder plays a critical role in the successful preparation of the aluminum alloy flux-cored wire.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4 Preparation and application of flux-cored wire","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Composition design of flux-cored wire\u003c/h2\u003e \u003cp\u003eThe in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire serves as a critical material for WAAM aluminum alloy components, particularly those requiring enhanced thermal insulation and compressive properties. During the WAAM process, the flux-cored powder within the wire undergoes a metallurgical reaction, generating an Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic phase. This phase not only enhances the strength of the deposited metal but also significantly reduces its thermal conductivity. The alloying elements in the in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire include Cu, Mn, Ti, V, Zr, and NiO. Among these, Mn, Ti, V, and Zr play a pivotal role in ensuring the comprehensive mechanical properties of the deposited metal. Notably, during the WAAM process, NiO reacts with the aluminum strip to form both the Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic phase and Ni, thereby further improving the thermal insulation and compressive properties of the aluminum alloy components. Additionally, to enhance arc stability, a small quantity of NaF is incorporated into the cored wire as an arc stabilizer. The specific content of the alloying elements (W\u003csub\u003e1\u003c/sub\u003e) in the cored wire is listed in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDesign composition of Al-Cu-NiO cored wire deposited metal (Wt%)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTi\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eZr\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNiO\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAl\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5.7–6.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.2–0.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.05–0.15\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1–0.15\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.05–0.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e≤ 2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eBal.\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003eThe diverse alloying elements present within the deposited metal are derived from the flux-cored powder contained in the flux-cored wire, facilitated through droplet transfer mechanisms. To achieve the precise composition of each alloying element within the deposited metal, as specified in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, stringent control over the elemental composition within the cored wire is imperative. The quantitative relationship between the content (\u003cem\u003eW\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e) for each constituent element present within said layer alongside their respective concentrations (\u003cem\u003eW\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e), may be expressed mathematically via Eq.\u0026nbsp;(4):\u003c/p\u003e \u003cdiv id=\"Equa\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:{w}_{1}={w}_{2}\\ast\\:\\phi\\:\\ast\\:\\epsilon\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\text{(}\\text{4}\\text{)}$$\u003c/div\u003e \u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cem\u003eφ\u003c/em\u003e represents the filling rate of the cored wire, while ε denotes the transition coefficient of the alloying elements. During WAAM, the high instantaneous temperature of the arc may lead to significant burn-off of alloying elements in the flux-cored powder. As a result, not all alloying elements within the cored wire fully transfer into the deposited metal. To quantify this effect, a transition coefficient (ε) is introduced to characterize the efficiency with which each element transitions from the cored wire to the deposited metal. The experimentally determined transition coefficients for the alloying elements investigated in this study are listed in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eElement Transition Coefficients\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTi\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eZr\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNiO\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.93\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003eThe ceramic aluminum alloy flux-cored wire is prepared by 1060 aluminum tape coated powder. The filling rate \u003cem\u003eφ\u003c/em\u003e is defined as the maximum amount of core powder that can be coated per unit length by a U-shaped aluminum strip, which is constrained by the strip's width and thickness. Specifically, φ is calculated as the ratio of the mass of the powder core (\u003cem\u003eW\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e) to the combined mass of the powder core (\u003cem\u003eW\u003c/em\u003e\u003csub\u003e3\u003c/sub\u003e) and the aluminum strip (\u003cem\u003eW\u003c/em\u003e\u003csub\u003e4\u003c/sub\u003e) over a 1-meter length of the strip. The filling rate can be expressed mathematically as Eq.\u0026nbsp;(\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e5\u003c/span\u003e)\u003csup\u003e[37]\u003c/sup\u003e:\u003c/p\u003e \u003cdiv id=\"Equ4\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$$\\:\\phi\\:=\\frac{{w}_{3}}{{w}_{3}+{w}_{4}}\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:$$\u003c/div\u003e \u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eIt can be seen from Eq.\u0026nbsp;(4)-(\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e5\u003c/span\u003e) that the higher the filling rate, the greater the weight of the powder core, and the higher the content of each element in the deposited metal. However, due to the easy work hardening during the drawing process of aluminum alloy, the core powder of the flux-cored wire is too much, and the fracture tendency of the wire is greater. Combined with the previous test and theoretical calculation, the filling rate of aluminum alloy flux-cored wire is 15%. According to Eq.\u0026nbsp;(4)-(\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e5\u003c/span\u003e), combined with Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the content of each alloy element except NiO in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e is taken as the lowest value. The content of each alloy element in the cored wire is calculated as shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The nominal content of NiO in the deposited metal of the cored wire is 2 wt.%.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe ratio of alloy core powder in flux-cored wire (Wt%)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTi\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eZr\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNiO\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNaF\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eAl\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e47.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.67\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.83\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.95\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14.34\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eBal.\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003e4.2 The karl index of core powder\u003c/h3\u003e\n\u003cp\u003eThe powder core is primarily composed of Al, Cu, and NiO. Based on the findings from multiple experimental trials, when the particle size of NiO is 50 µm, the resulting second-phase particles exhibit suitable dimensions and good bonding performance with the matrix. Therefore, following the control variable method, the particle sizes of the two ceramic components are first determined. After establishing the particle sizes of the ceramic powders, Al and Cu powders are identified as the primary factors influencing the fluidity of the core powders. According to the flux-cored wire composition in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, core powders with different particle sizes of Al and Cu are prepared. Specifically, in the first group (#1–#4), the Cu powder particle size is 250 µm, the NiO particle size is 50 µm, and the Al powder particle size varies sequentially at 150 µm, 200 µm, 250 µm, and 300 µm. In the second group (#5–#7), the Al powder particle size is fixed at 300 µm, the NiO particle size is 50 µm, and the Cu powder particle size varies at 150 µm, 200 µm, and 300 µm. Figure\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e presents the bulk density, tap density, angle of repose test results, and particle size screening process for the core powders. The fluidity test results for the mixed core powders with varying particle sizes are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe Karl index \u003cem\u003eFI\u003c/em\u003e is used to evaluate the fluidity of the core powder. When \u003cem\u003eFI\u003c/em\u003e is greater than 70, it indicates that the core powder has good fluidity. When \u003cem\u003eFI\u003c/em\u003e is less than 40, it indicates that the flowability of the core powder is very poor. When \u003cem\u003eFI\u003c/em\u003e is between 40 and 70, the liquidity is moderate. The Carl index \u003cem\u003eFI\u003c/em\u003e can be calculated by Eq.\u0026nbsp;(\u003cspan refid=\"Equ5\" class=\"InternalRef\"\u003e6\u003c/span\u003e)\u003csup\u003e[38]\u003c/sup\u003e:\u003c/p\u003e\u003cdiv id=\"Equ5\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ5\" name=\"EquationSource\"\u003e\n$$\\:FI=F1+F2+F3+F4\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e6\u003c/div\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cem\u003eF1\u003c/em\u003e∼\u003cem\u003eF4\u003c/em\u003e is the Carl index corresponding to the angle of repose \u003cem\u003eθ\u003c/em\u003e\u003csub\u003e\u003cem\u003erp\u003c/em\u003e\u003c/sub\u003e, the degree of compression \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e, the flat angle \u003cem\u003eθ\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e and the uniformity \u003cem\u003eU\u003c/em\u003e, respectively. The conversion relationship between the Karl index \u003cem\u003eFI\u003c/em\u003e and the flowability index can be found in the national standard GB/T 31057.3–2018. According to Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, the particle size of Al powder has the greatest influence on the particle size of mixed core powder. Under the limited process combination, for the Al-Cu-NiO alloy system wire, when the Al particle size is 300 µm, the Cu particle size is 250 µm, and the mixed core powder \u003cem\u003eFI\u003c/em\u003e is 89, indicating that the Al particle size in the core powder is 300 µm. When the Cu particle size is 250 µm, the mixed core powder has good fluidity, which is beneficial to the preparation of ceramic aluminum alloy flux-cored wire.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFlowability index of core powder and corresponding \u003cem\u003eFI\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eθ\u003c/em\u003e\u003csub\u003e\u003cem\u003erp\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eθ\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eU\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eFI\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e73.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.9\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e86.0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e31.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e88.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e89.0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e41.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e71.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e39.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19.9\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e72.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e39.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e73.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e\n\u003ch3\u003e4.3 Surface forming of flux-cored wire\u003c/h3\u003e\n\u003cp\u003eFigure\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e is the macroscopic morphology and schematic diagram of the in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e cored wire prepared by the above drawing-reducing method. From the cross-sectional view of the wire, it can be seen that the core powder is coated by the aluminum strip, and the wire presents a typical sandwich structure. The outer layer is a rolled aluminum strip, and the memory is the core powder particles. There are no obvious gaps and cracks on the surface of the wire, and the forming is better.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe surface quality of ceramic aluminum alloy flux-cored wire is a critical factor influencing the stability of wire feeding during WAAM. The surface morphology of the SiC-containing ceramic aluminum alloy flux-cored wire was observed using a scanning electron microscope at 30× and 50× magnification, as shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ea and b. As evident from the figures, the overlap formed by the closed overlap O-type wire is clearly visible. The wire surface is flat, smooth, and free of obvious scratches, pits, or burr defects. Compared to the commercial aluminum alloy solid wire (Figs.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003ec and d), the surface quality of the lapped O-type ceramic aluminum alloy flux-cored wire prepared by the drawing-reducing method is also superior.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.4 Deposition processability of flux-cored wire\u003c/h2\u003e \u003cp\u003eThe CMT-CYCLE welding mode was adopted. The shielding gas was high-purity argon and the gas flow rate was 20 L/min. Deposition current 85 A, voltage 9.8 V. Figure\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003e presents the forming and surface roughness of the deposited metal from the cored wire. When the NiO content is 2 wt.%, the deposited strut exhibits stable formation, with a well-formed surface and a noticeable step effect. No defects such as pores or cracks are observed, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003ea. The surface profile of the rod was measured using a surface profile measuring instrument, with each rod measured three times. The surface profile fluctuation was found to be 55 µm. Figure\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e14\u003c/span\u003eb shows that the surface profile fluctuation of rods deposited by different self-generated Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic flux-cored wire is consistently below 60 µm, demonstrating high smoothness. These results indicate that the cored wire prepared by the aluminum tape coating method possesses excellent formability.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e presents a full-cycle droplet transfer diagram of WAAM process using flux-cored wire. The arc ignition occurs through contact arcing, followed by stable combustion. Droplet transfer occurs in short-circuit mode with minimal spattering due to the excellent arc stability. This high stability performance is attributed to NaF additives in the cored wire. [Na] (ionization potential: 5.14 V) ionize more readily than [Al] (5.99 V) or [H] (13.6 V). During arcing, thermal decomposition of NaF produces abundant Na\u003csup\u003e+\u003c/sup\u003e, significantly increasing charged particle density in the arc plasma. Concurrently, the liberated F\u003csup\u003e−\u003c/sup\u003e combine with H\u003csup\u003e+\u003c/sup\u003e in the molten pool to form HF, effectively reducing hydrogen content in the deposited metal and suppressing hydrogen porosity. The results demonstrate that developed in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire enables stable arc maintenance and consistent droplet transfer throughout the WAAM.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e16\u003c/span\u003e depicts the current and voltage profiles of droplet transfer during three consecutive cycles of rod made via WAAM using in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire. Notably, the interval time between each cycle is 200 ms, and the current and voltage remain relatively stable throughout the process. The peak change trend is consistent with the droplet transition characteristics presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e15\u003c/span\u003e, and the signal curve has no significant fluctuations. This consistency demonstrates the robust manufacturability of the developed Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire in the WAAM process.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e4.5 Deposited metal composition of flux-cored wire\u003c/h2\u003e \u003cp\u003eBulk samples with a size of 20×20×40 mm were deposited on 1060 aluminum alloy plate using developed aluminum alloy flux-cored wire with a nominal content of NiO of 2 wt.%. In order to prevent the substrate from diluting the composition of the bulk, the bulk with a height of 20 mm in the upper part of the deposited bulk was taken as the test sample, that is, the bulk with a size of 20×20×20 mm was obtained for testing the chemical composition of the deposited metal. The chemical composition of the sample was tested by ARL 4460 direct-reading spectrometer. Due to the unstable content of O measured by the direct-reading spectrometer, the content of Ni was used to evaluate the amount of NiO introduced. The test results are shown in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. Comparing Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, it can be seen that the content of all elements in the deposited metal is close to the design value. Among them, the Ni content is 1.532 wt.%. The actual NiO content is 1.949 wt.% calculated by the relative atomic mass ratio conversion (The mass fraction of Ni in NiO is 78.6 wt.%), which is basically consistent with the design introduction. It shows that the deposited metal composition of the cored wire prepared by the aluminum strip method is in line with the design value, and this method is feasible.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe measured content of cored wire deposited metal (Wt%)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTi\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eZr\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNi\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eAl\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eⅢ\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.694\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.299\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.047\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.119\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.094\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1.532\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eBal.\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e4.6 Deposited metal microstructure and properties of flux-cored wire\u003c/h2\u003e \u003cp\u003eThe microstructure of the metal deposited using an in-situ Al₂O₃ ceramic aluminum alloy flux-cored wire (composition: Cu: 47.5 wt.%, Mn: 2.67 wt.%, Ti: 0.83 wt.%, V: 0.89 wt.%, Zr: 0.95 wt.%, NiO: 7.17 wt.%, NaF: 1 wt.%, Al: residual) is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003e. The deposited metal predominantly consists of equiaxed crystals, comprising α-Al as the primary phase and Al₂Cu precipitates dispersed within the grain structure. Additionally, a limited number of pores are observed in the deposited material. Scanning electron microscopy (SEM) images reveal a significant presence of Al₂Cu strengthening phases, which are evenly distributed within the grains of the deposited metal, as illustrated in Figs.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003ea and b.To further elucidate the internal phase composition of the deposited metal, a detailed characterization was conducted using transmission electron microscopy (TEM) and energy spectrum analysis. As shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e17\u003c/span\u003ec and d, the TEM images reveal the presence of nanoparticles within the deposited metal matrix. Energy spectrum analysis confirms the presence of a significant amount of oxygen (O) in addition to aluminum (Al) in this region. The nanoparticles consist of Al₂O₃ ceramic phases, which exhibit an ellipsoidal morphology, and Al₂Cu phases, which appear as platelet-like structures with an average size of approximately 50 nm. These findings demonstrate that the specialized aluminum alloy flux-cored wire for WAAM can be successfully prepared through a drawing and diameter reduction process, thereby achieving the desired compositional requirements.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e summarizes the mechanical properties and thermal conductivity of the as-deposited metal fabricated using in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire. A custom-developed Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire was employed for the deposition process, specifically for fabricating the straight wall structure. The as-deposited metal exhibited an average tensile strength of 253.4 MPa and a room-temperature thermal conductivity of 88.8 W/(m·K).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMechanical properties and thermal Conductivity of deposited Metals\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e#\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTensile strength\u003c/p\u003e \u003cp\u003e(MPa)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAverage\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eThermal conductivity at\u003c/p\u003e \u003cp\u003e25°C(W / (m∙K))\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAverage\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e252.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e253.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e89.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e88.8\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e258.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e88.6\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e249.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e88.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eAs demonstrated by the analysis, the chemical composition of the deposited metal derived from the in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic aluminum alloy flux-cored wire closely matches the design specifications. The microstructure of the deposited metal predominantly consists of α-Al grains, with the presence of Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic phase and Al\u003csub\u003e2\u003c/sub\u003eCu phase, which collectively exhibit both favorable mechanical properties and relatively low thermal conductivity.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e4.7 Application of flux-cored wire\u003c/h2\u003e \u003cp\u003eThe aircraft outer skin has the following dimensional specifications: a height of 250 mm, a top outer diameter of 265 mm, a bottom outer diameter of 135 mm, and a thickness of 10 mm. The structural model of the component is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig18\" class=\"InternalRef\"\u003e18\u003c/span\u003ea. The developed ceramic aluminum alloy flux-cored wire was employed to fabricate the aircraft skin. The substrate dimensions is 500 500×20 mm. The model was sliced using Eclipse software with a layer height of 3 mm. The WAAM process was conducted with a deposition current of 125 A and a deposition rate of 0.6 m/min. The aircraft skin fabricated via this process is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig18\" class=\"InternalRef\"\u003e18\u003c/span\u003eb. It can be seen that the surface of the aircraft skin exhibits good formation quality, with no noticeable defects such as collapse or cracking. Non-destructive evaluation of the deposited metal revealed no significant defects, including pores or incomplete fusion, which can be attributed to the excellent arc stability and low spatter rate of the developed cored wire. Furthermore, dimensional measurements using three-dimensional metrology indicated that the deviation between the fabricated component and the design model is within ± 1 mm, confirming that the manufacturing accuracy meets the specified requirements.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e "},{"header":"5 Conclusions","content":"\u003cp\u003eAiming at the preparation requirements of ceramic aluminum alloy flux-cored wire for WAAM, this paper developed the preparation of cored wire, and formulated the drawing process of aluminum alloy flux-cored wire and the heat treatment process of aluminum strip. Taking the Al-Cu-NiO system ceramic aluminum alloy flux-cored wire as an example, the flux-cored wire was trial-produced and applied. The main conclusions are as follows :\u003c/p\u003e\u003cp\u003e( 1 ) In this paper, a roll unit composed of three forming rolls and three sets of closed rolls is designed. A drawing die with 12 sets of different diameters is also designed. The single compression ratio is controlled at 20%. The preparation equipment of aluminum alloy flux-cored wire composed of wire forming unit, drawing reduction unit and wire rolling unit is integrated, which can realize the preparation of aluminum alloy flux-cored wire with a minimum diameter of 1.2 mm.\u003c/p\u003e\u003cp\u003e(2) When the particle size of Al is 300 µm, the particle size of Cu is 250 µm, and the particle size of Si is 200 µm, the core powder has high fluidity. The pre-heat treatment process parameters of aluminum strip were determined : heating temperature 230°C, holding time 120 min, cooling method: air cooling, after 12 drawing and reducing processes, the preparation of ceramic aluminum alloy flux-cored wire with diameter of 1.2 mm was realized.\u003c/p\u003e \u003cp\u003e(3) The Al-Cu-NiO aluminum alloy flux-cored wire was developed. Using the developed Al-Cu-NiO flux-cored wire, the arc combustion is stable, the droplet transition is stable, and the spatter is small. The deposited metal is composed of α-Al and Al\u003csub\u003e2\u003c/sub\u003eCu precipitates dispersed in the grain, and the in-situ Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic phase is nano-sized. The outer skin of the aircraft is prepared by using the developed aluminum alloy flux-cored wire, which has high forming performance.\u003c/p\u003e "},{"header":"Declarations","content":"\u003ch2\u003e\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\u003c/h2\u003e \u003cp\u003e \u003cstrong\u003eConflict of interest\u003c/strong\u003e \u003cp\u003eThe authors declare no competing interestss.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work is supported by National Natural Science Foundation of China (51790174).\u003c/p\u003e\u003ch2\u003eAuthor contribution\u003c/h2\u003e \u003cp\u003eBo Zheng conducted experiments, sanalysis, and wrote the manuscript; Shengfu Yu and Zhenyu Yu made contributions to research concept and manuscript preparation; Lun Tang assisted in analysis through constructive discussions.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e \u003cp\u003eThe data that has been used is confidential.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eS. S. Li, X. Yue, Q. Y. Li, H. L. Peng, B. X. Dong, T. S. Liu, et al. Development and applications of aluminum alloys for aerospace industry. Journal of Materials Research and Technology, 2023, 27: 944-983. \u003cstrong\u003ehttps://doi.org/10.1016/j.jmrt.2023.09.27\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eA. P. Nagalingam, M. Shamir, E. B. Tureyen, A. R. C. Sharman, O. Poyraz, E. Yasa. Recent progress in wire‑arc and wire‑laser directed energy deposition (DED) of titanium and aluminium alloys. The International Journal of Advanced Manufacturing Technology, 2025, 136: 2035-2073. \u003cstrong\u003ehttps://doi.org/10.1007/s00170-024-14967-w\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eA. Hamrani, F. Z. Bouarab, A. Agarwal, K. Ju, H. Akbarzadeh. Advancements and applications of multiple wire processes in additive manufacturing: a comprehensive systematic review. Virtual and Physical Prototyping, 2023, 18(1): 1-34. \u003cstrong\u003ehttps://doi.org/10.1080/17452759.2023.2273303\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eA. G. Ortega, L. C. Galvan, M. Salem, K. Moussaoui, S. Segonds, S. Rouquette, et al. Characterization of 4043 aluminum alloy deposits obtained by wire and arc additive manufacturing using a Cold Metal Transfer process. Sciencce and Technology of Welding and Joining, 2019, 24(6): 538-547. \u003cstrong\u003ehttps://doi.org/10.1080/13621718.2018.1564986\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eJ. K. Wang, Q. K. Shen, X. D. Kong, X. Z. Chen. Arc Additively Manufactured 5356 Aluminum Alloy with Cable-Type Welding Wire: Microstructure and Mechanical Properties. Journal of Materials Engieering and Performance, 2021, 30: 7472-7478. \u003cstrong\u003ehttps://doi.org/10.1007/s11665-021-05905-y\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eY. M. Huang, S. S. Hou, T. Sun, L. J. Yang, S. S. Li, S. B. Chen, et al. An improved model of porosity formation during pulsed GTA welding of aluminum alloys, Materials Science and Engineering B, 2018, 238: 122-129. \u003cstrong\u003ehttps://doi.org/10.1016/j.mseb.2018.11.012\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eP. A. Colegrove, J. Donoghue, F. Martina, J. L. Gu, P. Prangnell, J. Honnige. Application of bulk deformation methods for microstructural and material property improvement and residual stress and distortion control in additively manufactured components. Scripta Materialia, 2017, 135: 111-118. \u003cstrong\u003ehttps://doi.org/10.1016/j.scriptamat.2016.10.031\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eJ. L. Gu, X. S. Wang, J. Bai, J. L. Ding, S. Williams, Y. C. Zhai, et al. Deformation microstructures and strengthening mechanisms for the wire+arc additively manufactured Al-Mg4.5Mn alloy with inter-layer rolling. Materials Science and Engineering A, 2017, 712: 292-301. \u003cstrong\u003ehttps://doi.org/10.1016/j.msea.2017.11.113\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eJ. L. Gu, J. L. Ding, S. W. Williams, H. M. Gu, P. H. Ma, Y. C. Zhai. The effect of inter-layer cold working and post-deposition heat treatment on porosity in additively manufactured aluminum alloys. Journal of Materials Processing Technology, 2016, 230: 26-34. \u003cstrong\u003ehttps://doi.org/10.1016/j.jmatprotec.2015.11.006\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eS. Y. Zhou, J. Y. Wang, G. Yang, B. Wu, H. Xie, K. Wu, et al. Periodic microstructure of Al\u0026ndash;Mg alloy fabricated by inter-layer hammering hybrid wire arc additive manufacturing: Formation mechanism, microstructural and mechanical characterization. Materials Science and Engineering A, 2022, 860: 144314. \u003cstrong\u003ehttps://doi.org/10.1016/j.msea.2022.144314\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eX. W. Fang, L. J. Zhang, G. P. Chen, K. Huang, F. Xue, L. Wang, et al. Microstructure evolution of wire-arc additively manufactured 2319 aluminum alloy with interlayer hammering. Materials Science and Engineering A, 2021, 800: 140168. \u003cstrong\u003ehttps://doi.org/10.1016/j.msea.2020.140168\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eR. Z. Yu, S. F. Yu, Z. Y. Yu, B. Zheng, G. Z. Yu. Effect of inter-layer rotary friction processing on porosity of arc-directed energy-deposited high-strength aluminum alloys. Journal of Materials Processing Technology, 2023, 316: 117951. \u003cstrong\u003ehttps://doi.org/10.1016/j.jmatprotec.2023.117951\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eR. Z. Yu, S. F. Yu, Z. M. Wang, G. Z. Yu. Strengthening of wire arc additive manufactured aluminum alloy through interlayer rotary friction processing. Science and Technology of Welding and Joining, 2023, 28(9): 923-931. \u003cstrong\u003ehttps://doi.org/10.1080/13621718.2023.2247271\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eC. S. He, J. X. Wei, Y. Li, Z. Q. Zhang, N. Tan, G. W. Qin, et al. Improvement of microstructure and fatigue performance of wire-arc additive manufactured 4043 aluminum alloy assisted by interlayer friction stir processing. Journal of Materials Science and Technology, 2023, 133: 183-194. \u003cstrong\u003ehttps://doi.org/10.1016/j.jmst.2022.07.001\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eP. Jin, Y. B. Liu, F. X. Li, Q. J. Sun. Realization of structural evolution in grain boundary, solute redistribution and improved mechanical properties by adding TiCnps in wire and arc additive manufacturing 2219 aluminium alloy. Journal of Materials Research and Technolgoy, 2021, 11: 834-848. \u003cstrong\u003ehttps://doi.org/10.1016/j.jmrt.2021.01.030\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eF. R. Chen, Y. H. Yang, C. Chen, Q. X. Wang, R. J. Xun. Effect of La\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e particle size on the microstructure and properties of Al-Si alloys deposited via wire arc additive manufacturing. Journal of Manufacturing Process, 2021, 68: 523-533. \u003cstrong\u003ehttps://doi.org/10.1016/j.jmapro.2021.05.069\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eP. Jin, Y. B. Liu, Q. J. Sun. Evolution of crystallographic orientation, columnar to equiaxed transformation and mechanical properties realized by adding TiCps in wire and arc additive manufacturing 2219 aluminum alloy. Additive Manufacturing, 2021, 39: 101878. \u003cstrong\u003ehttps://doi.org/10.1016/j.addma.2021.101878\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eA. K. Sinha, K. P. Yagati. Wire Arc Additive Manufacturing of Al-Cu Alloy-Grain Refinement, Strengthening and Thermal Simulation. Silicon, 2024, 16: 441-461. \u003cstrong\u003ehttps://doi.org/10.1007/s12633-023-02667-1\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eJ. H. Martin, B. D. Yahata, J. M. Hundley. 3D printing of high-strength aluminium alloys. Nature, 2017, 549: 365-369. \u003cstrong\u003ehttps://doi.org/10.1038/nature23894\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eH. S. Ren, Y. B. Liu, H. Y. Kong, C. Y. Song, Y. F. Xie, Q. J. Sun. Microsture and mechanical properties of Al-Cu alloy during wire and arc additive manufacturing by adding micron TiB\u003csub\u003e2\u003c/sub\u003e particles. Virtual and Physical Prototyping, 2024, 19(1): 1-18. \u003cstrong\u003ehttps://doi.org/10.1080/17452759.2024.2351170\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eY. N. Hu, F. R. CHEN, S. L. Cao, Y. F. Fan, R. J. Xie. Improvement of microstructure and mechanical properties of CMT wire arc additive manufacturing Al-Si alloy deosition via interlayer coating TiC nanoparticles. Materials Today Communications, 2024, 38: 107851. \u003cstrong\u003ehttps://doi.org/10.1016/j.mtcomm.2023.107851\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eT. Klein, A. Arnoldet, R. Lahnsteiner, M. Schnall. Microstructure and mechanical properties of a structurally refined Al\u0026ndash;Mg\u0026ndash;Si alloy for wire-arc additive manufacturing. Materials Science and Engineering: A, 2022, 830: 142318. \u003cstrong\u003ehttps://doi.org/10.1016/j.msea.2021.142318\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eH. Su, W. Gao, Z. H. Feng, Z. Lu. Processing microstructure and tensile properties of nano-sized Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e particle reinforced aluminum matrix composites. Materials and Design, 2016, 36: 590-596.\u003cstrong\u003e https://doi.org/10.1016/j.matdes.2011.11.064\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eN. Mclean. M. J. Bermingham, P. Colgrove, A. Sales, M. S. Dargusch. Understanding the grain refinement mechanisms in aluminium 2319 alloy produced by wire arc additive manufacturing. Science and technology of welding and joining, 2022, 27(6): 479-489. \u003cstrong\u003ehttps://doi.org/10.1080/13621718.2022.2064704\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eJ. X. Sun, H. S. Yu, D. X. Zeng, P. Shen. Wire-powder-arc additive manufacturing: A viable strategy to fabricate carbide cermics/aluminum alloy multi-material structures. Additive Manufacturing, 2022, 51: 102637. \u003cstrong\u003ehttps://doi.org/10.1016/j.addma.2022.102637\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eX. P. Song, J. K. Niu, J. K. Huang, D. Fan, S. R. Yu, Y. J. Ma, et al. The Effect of B\u003csub\u003e4\u003c/sub\u003eC Powder on Properties of the WAAM 2319 Al Alloy. Materials, 2023, 436(16): 1-14. \u003cstrong\u003ehttps://doi.org/10.3390/ma16010436\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eM. Sokoluk, C. Z. Cao, S. H. Pan, X. C. Li. Nanoparticle-enabled phase control for arc welding of unweldable aluminum alloy 7075. Nature communications, 2019, 98(10): 1-8.\u003cstrong\u003ehttps://doi.org/10.1038/s41467-018-07989-y\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eW. Q. Liu, C. Z. Cao, J. Q. Xu, X. J. Wang, X. C. Li. Molten salt assisted solidification nanoprocessing of Al-TiC nanocomposites. Materials Letters, 2016, 18: 392-395.\u003cstrong\u003ehttps://doi.org/10.1016/j.matlet.2016.09.023\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eG. Langelandsvik, M. Eriksson, O. M. Akselsen, H. J. Roven. Wire arc additive manufacturing of AA5183 with TiC nanoparticles. The International Journal of Advanced Manufacturing Technology, 2022, 119: 1047-1058.\u003cstrong\u003ehttps://doi.org/10.1007/s00170-021-08287-6\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eD. Oropeza, D. C. Hofmann, K. Williams, S. Firdosy, P. Bordeenithikasem, M. Sokoluk, et al. Welding and additive manufacturing with nanoparticle-enhanced aluminum 7075 wire. Journal of Alloys and Compounds, 2020, 834: 154987. \u003cstrong\u003ehttps://doi.org/10.1016/j.jallcom.2020.154987\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eQ. Y. Liu, H. B. Mi, L. Y. Feng, W. Guo, B. Y. He. A critical overview of welding and directed energy deposition with flux-cored wires. Journal of Manufacturing Porcesses, 2025, 142: 231-268. \u003cstrong\u003ehttps://doi.org/10.1016/j.jmapro.2025.03.097\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eV. P. Lyalyakin, D. B. Slinko, V. A. Denisov. Preparation of Composite Coatings by Electric Arc Spraying Using Flux-Cored Wires. Russian Metallurgy, 2022, 13: 1753-1739. \u003cstrong\u003ehttps://doi.org/10.1134/S0036029522130183\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eY. J. Zhou, S. M. Yin, Y. Jiang, Q. L. Zhou, J. B. Peng, Y. W. Yan. Wire and arc additive manufacturing fabrication of ODS-RAFM steels and preliminary evaluation on microstructures and mechanical properties. Journal of Nuclear Materials, 2022, 572: 154068. \u003cstrong\u003ehttps://doi.org/10.1016/j.jnucmat.2022.154068\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eN. H. Xiao, J.Y. Liu. Cold bending forming technique. First Edition.Chemical Industry Press，2008.\u003c/li\u003e\n\u003cli\u003eJ. F. Leng, Y. F. Dong, B. H. Ren, X. L. Xu, B. Zhu, S. Tian. Effect of Rolling Deformation on Microstructure and Properties of 7085 Aluminum Alloy. Physics of Metals and Metallography, 2021, 122: 1543-1550. \u003cstrong\u003ehttps://doi.org/10.1134/S0031918X21140131\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eS. C. Yang, Y. B. Chen. Modern advanced engine technology. Design and Manufacture of Diesel Engine, 2001, 1: 8-14.\u003cstrong\u003ehttps://doi.org/10.3969/j.issn.1671-0614.2001.01.002\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eG. H. Wu, K. Q. Lv. Mathematical analysis of stability of powder filling rate of flux-cored wire. Welding Technology, 2011, 40(9): 32-34.\u003cstrong\u003ehttps://doi.org/10.1134/S0031918X21140131\u003c/strong\u003e\u003c/li\u003e\n\u003cli\u003eGB/T 310557.3. Granular materials-Physical properties-Part 3: Fluidity index, 2018\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"welding-in-the-world","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"witw","sideBox":"Learn more about [Welding in the World](https://www.springer.com/journal/40194)","snPcode":"40194","submissionUrl":"https://www.editorialmanager.com/witw/","title":"Welding in the World","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Wire arc additive manufacuting, Flux-cored wires, Aluminum alloy, Heat treatment","lastPublishedDoi":"10.21203/rs.3.rs-6699297/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6699297/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCeramic phase modification is a effective method to improve the performance of wire arc additive manufacturing (WAAM) aluminum alloy component. In this paper, a preparation method of ceramic aluminum alloy flux-cored wire was developed. An advanced apparatus was developed for the preparation of flux-cored wires. The preparation system comprises three integral units: a wire forming module, a drawing module, and a coiling module. The wire forming module features a configuration of three forming rollers and three closed dies, while the drawing and reduction module incorporates 12 sets of wire drawing dies with varying diameters, with each stage maintaining a controlled compression ratio of 20%. The fluidization properties of the core powder mixture were systematically examined, revealing that optimal powder flow characteristics were achieved when the constituent particles were sized as follows aluminum particles at 300 \u0026micro;m, copper particles at 250 \u0026micro;m, and silicon particles at 200 \u0026micro;m. The pre-heat treatment parameters for the aluminum strip substrate were optimized, with the process conditions established as follows heating temperature of 230\u0026deg;C, soaking duration of 120 min, and air cooling as the cooling method. Through a sequential series of 12 drawing and reduction operations, a 1.2 mm diameter Al-Cu-NiO aluminum alloy flux-cored wire was successfully fabricated. During the WAAM process employing the developed Al-Cu-NiO flux-cored wire, the process exhibited stable arc combustion, consistent droplet transfer, and minimal spatter. The developed flux-cored wire was successfully utilized to fabricate the aircraft skin, demonstrating high formability and suitability for such applications.\u003c/p\u003e","manuscriptTitle":"The preparation method and application of aluminum alloy flux-cored wire for wire arc additive manufacturing","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-27 07:08:09","doi":"10.21203/rs.3.rs-6699297/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-06-24T15:37:41+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-24T13:26:38+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Welding in the World","date":"2025-05-29T07:45:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-22T17:34:33+00:00","index":"","fulltext":""},{"type":"submitted","content":"Welding in the World","date":"2025-05-19T09:07:28+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"welding-in-the-world","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"witw","sideBox":"Learn more about [Welding in the World](https://www.springer.com/journal/40194)","snPcode":"40194","submissionUrl":"https://www.editorialmanager.com/witw/","title":"Welding in the World","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"3dc6f941-0928-4701-85cb-036db519ee9a","owner":[],"postedDate":"June 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-10-09T17:33:24+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-27 07:08:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6699297","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6699297","identity":"rs-6699297","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}