Tribo–Driven Evolution of Specific Nano–heterostructures to Achieve Exceptional Wear Resistance in Composites

Tribo–Driven Evolution of Specific Nano–heterostructures to Achieve Exceptional Wear Resistance in Composites | 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 Tribo–Driven Evolution of Specific Nano–heterostructures to Achieve Exceptional Wear Resistance in Composites Shuai Yang, Siyang Gao, Weihai Xue, Bi Wu, Deli Duan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6275026/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Aug, 2025 Read the published version in Advanced Composites and Hybrid Materials → Version 1 posted 11 You are reading this latest preprint version Abstract The study of the evolution of nano–heterostructures controlling tribological behavior is crucial for optimizing the wear resistance of composites. A novel NiAlTa/cBN composite produced by spark plasma sintering exhibited exceptional wear resistance, which is attributed to the tribo–layers with special nano–heterostructures induced by stress and temperature. At room temperature, an extremely low wear rate (10 –7 mm 3 ·N –1 ·m –1 ) and a low coefficient of friction (0.252) of the composite were attributed to the nanoscale amorphous tribo–layer. Amorphization was synergistically controlled by the plastic deformation–induced solid–state amorphization and oxidation processes. Tribo–induced amorphous layer accommodated the sliding–induced elastic–plastic deformation and virtually eliminated wear. At high temperatures, the plastic incompatibility and strain localization of the subsurface nanocrystalline layer mediated by dislocations, stacking faults, and deformation twins increased the wear rate. The formation of an amorphous tribo–oxide layer and oxidative cleaving effect reduced the fracture toughness of cBN particles and increased the tendency of crack nucleation and growth. Dislocations, stacking fault networks, and FCC → HCP phase transition synergistically increased the microplastic deformability and strain–hardening capacity of cBN particles and reduced the wear rate. Ta 3 N 5 nanoparticles generated by tribo–chemical reaction played a load–supporting and stress–transferring role in sliding wear. This work highlighted the significance of the tribo–induced evolution of the tribo–layers on the wear resistance of the composite. A strategy to achieve exceptional wear resistance by regulating the evolution of specific nano–heterostructures on the composite surfaces was proposed. Nano–heterostructures NiAlTa/cBN composites Wear resistance Wear mechanism Tribo–layer Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 INTRODUCTION Metal–ceramic composites become one of the core materials in advanced manufacturing by breaking through the performance limits of traditional metal materials through the precise design of components and structures [ 1 , 2 ]. The designability of properties (e.g., wear resistance) and engineering applicability of metal–ceramic composites are continuously expanded. A successful case is the use of MCrAlYX/cBN composites for turbine blade tips to achieve wear and impact resistance in aero–engines [ 3 ]. Unfortunately, conventional MCrAlYX/cBN composites can no longer meet the operating environment requirements of hot–end turbines (> 1000 ℃), and suffer from low high–temperature strength, severe wear, and difficulty in retaining ceramic particles [ 4 ]. A candidate NiAlTa/cBN composite is proposed. Due to the lack of in–depth studies on this composite, its failure mechanism in dry sliding wear is still unclear. Therefore, it is necessary to understand the wear mechanism comprehensively to guide the further optimization of material properties. The wear mechanism of metal–ceramic composites is influenced by the material composition (e.g., the ratio of metallic to ceramic phases) and microstructure (e.g., distribution and size of ceramic particles, interfacial bonding state). In high–temperature dry sliding wear, the wear mechanism of metal–ceramic composites shifts from being controlled by the delamination and oxidation of the metal to being related to the wear and fracture of the ceramic particles as the proportion of the ceramic phase increases [ 5 , 6 ]. The transition of the wear mechanism depends on the sensitivity of the internal structure or elements of the metal and ceramic to temperature and tribo–chemical reactions. Nanoscale ( 10 µm) affect the wear mechanism of composites by influencing the microcomposition, the tribo–oxidation behavior, and the evolution of the tribo–layer of the metal. For example, Al 2 O 3 ceramic particles altered the phase composition of the CoCrAlYTa material produced by laser-induction hybrid cladding, which transformed severe adhesive wear into micro–cutting mechanism with a low wear rate [ 7 ]. Adhesive wear characterized by a high wear rate and a high coefficient of friction caused by nanoparticles is undesirable [ 8 ]. Microceramic particles can significantly improve this disadvantage and impact resistance by modifying the interface contact state, but they may act as a source of cracks. In addition, the interfacial bonding state between metal and ceramic also exerts an important influence. Three–body abrasive wear caused by ceramic particle detachment due to weak interfacial bonding increases wear rate and coefficient of friction fluctuations. By applying a metal layer or an interfacial reaction layer on the ceramic particle surface to realize the wetting between metal and ceramic (e.g., the wettability of Co on WC [ 9 ], the formation of Ni₃Ti from TiC and Ni [ 10 ]), the transfer of effective load and the delay of interfacial exfoliation can be achieved to improve the wear resistance of composites. In high–temperature dry sliding wear, a transition in the wear mechanism of metal–ceramic composites has been defined as a function of temperature. This transition is closely related to the evolution of the tribo–layer on the metal and ceramic surfaces. The tribo–layer induced by sliding wear controls the wear process as it is where the friction energy is dissipated and accommodates the stress, speed, and temperature gradients. Oxides serve as the basic units that make up the tribo–layer. Generally, the tribo–layer is formed by repeated fragmentation, compaction, and sintering of oxide wear debris, which can accommodate elastic–plastic deformation and virtually eliminate wear [ 11 ]. For example, the CoCrAlYTaCSi/Al 2 O 3 composites underwent a transition from severe to mild wear as the temperature increased. After the formation of the tribo–layer, the wear rate of the composites was reduced by an order of magnitude [ 12 ]. Temperature usually influences the evolution of the tribo–layer and the wear mechanism by affecting the oxidation rate of the metal, the mode of mechanical deformation, and the sintering rate of the oxide wear debris. Currently, three mechanisms have been proposed to explain the evolution of the tribo–layer and the transformation of the wear mechanism [ 13 – 15 ], namely, the “metal debris” mechanism, the “oxidation–scratch–re–oxidation” mechanism, and the “complete oxidation” mechanism. However, the micromechanisms of chemical stability of ceramic particles in high–temperature sliding wear are not well investigated. Limited studies showed that the competition between oxygen–assisted surface decarburization and toughening of the nano–oxide tribo–layer of TiC particles in high–temperature sliding wear determined the wear mechanism of Fe–TiC composites [ 1 ]. Thus, it can be seen that the tribo–layers on the metal and ceramic surfaces may not be isolated from each other, and they are connected and together influence the wear mechanism of metal–ceramic composites. Besides the tribo–layers on the metal and ceramic surfaces, the microstructure evolution of the subsurfaces induced by sliding wear also affects the wear resistance of metal–ceramic composites. In general, plastic deformation layers triggered by plastic deformation mediated by dislocations, stacking faults, or deformation twins, individually or jointly, become one of the responses of the microstructure of the subsurface. These responses also include high–temperature–induced dynamic recrystallization [ 16 ], dislocation–mediated grain refinement [ 17 ], and grain boundary migration–controlled grain growth [ 18 ]. In high–temperature sliding wear, the subsurface plastic deformation layer is not directly involved in the sliding process, and it only serves as a load–bearing layer for the tribo–layer. The stability of the plastic deformation layer affects the tribological behavior of the composite. Strain localization due to the continuous accumulation of plastic strain leads to crack nucleation at the metal–ceramic interface. For example, cracks originating from Al 2 O 3 particles weakened the mechanical supporting effect on the tribo–layer, resulting in a significant increase in the wear rate of CoNiCrAlY/Al 2 O 3 composites [ 19 ]. In addition, the microstructure of ceramic particles changes with load and temperature. For example, the movement and multiplication of dislocations induced by friction loading caused microplastic deformation of WC ceramic particles at high temperatures [ 20 ]. In high–temperature sliding wear, an in–depth study of the evolution of nano–heterostructures controlling the tribological behavior is crucial for optimizing the wear resistance of composites. Therefore, spark–plasma–sintered NiAlTa/cBN composites are used as a model system to investigate the stress– and temperature–induced evolution of the tribo–layers with specific nano–heterostructures of the metal and ceramic surfaces and their effects on the tribological behavior. This work highlighted the significance of the tribo–induced evolution of the tribo–layers on the wear resistance of the composite. A strategy to achieve exceptional wear resistance by regulating the evolution of specific nano–heterostructures on the composite surfaces was proposed. RESULTS AND DISCUSSION Material Characterization. Figure 1 a shows the preparation process of NiAlTa/cBN composites, including powder mixing and spark plasma sintering (SPS). The principle of SPS is demonstrated in it. The mixed powder is placed in a graphite die. The powder particles undergo plastic deformation, rearrangement, and diffusion joining to achieve material densification under the synergistic effect of pulsed current, pressure, and rapidly elevated temperature. Figure 1 b displays the microscopic morphology of NiAlTa/cBN mixed powders. The size statistic in the inset illustrates that the average particle size of the metal powder is about 40 µm. The microscopic morphology and EDS mapping of Ni–coated cBN particles are showed in Fig. 1 c. The Ni layer is prepared by chemical plating, which is well combined with cBN particles. High–resolution TEM photograph and fast fourier transform map (FFT map) confirm that the BN particles are characterized by a typical face–centered cubic (FCC) structure (Fig. 1 d). The presence of defects such as lattice distortions and vacancies indicates that the cBN particles are non–stoichiometric, which is caused by the filling of vacancies of nitrogen atoms by oxygen atoms (BN 1–x [ V N ]) [ 21 ]. The atomic model of the FCC structure of cBN is shown in Fig. 1 d. The tribological behavior of the composites depends on their microstructure and phase composition. Figure 1 e illustrates the backscattered electron morphology (BSE) of NiAlTa/cBN composites. A good infiltration between cBN particles and NiAlTa metal is achieved. The difference in the contrast indicates that besides the cBN particles, the gray matrix phase and white nanoparticles diffusely distributed in its interior or grain boundaries are found in the NiAlTa/cBN composites. TEM bright field image and EDS mapping of the gray phase and white nanoparticles are shown in Fig. 1 f. White nanoparticles are enriched with the heavy metal element Ta. High–resolution TEM photograph and fast fourier transform (FFT) map at their interfaces show that the gray phase and white nanoparticles are β–NiAl with B2–type ordered body–centered cubic structure and (Ni, Al)Ta with C14–type hexagonal structure, respectively (Fig. 1 g). (Ni, Al)Ta phase is preferentially formed at the grain boundaries of the β–NiAl phase. (Ni, Al)Ta phase is a topological close–packed phase (TCP) with a MgZn 2 –type laves lattice. Compared with the body–centered cubic structure, this crystal structure has higher lattice friction giving it high hardness and high–temperature stability [ 4 ]. In addition, an incoherent interface of cubic to hexagonal structure between the β–NiAl phase and the (Ni, Al)Ta phase is observed. The poor lattice match and weak interfacial bonding strength are highly susceptible to becoming a source of cracks and reduce the toughness of the composites [ 2 ]. XRD result reconfirms the presence of these phases (Fig. 1 h). The dispersion of ceramic particles directly affects the tribological behavior of the composites. The distribution of cBN particles was analyzed by a microscopic computed tomography (CT) technique. The results are displayed in Fig. 1 i. The CT results show that the cBN particles are uniformly dispersed in NiAlTa metal. The good dispersion of cBN particles is favorable for the wear resistance of the composites. Nano–hardness and elastic modulus are fundamental quantitative parameters to measure the mechanical properties of materials at the micro– and nanoscale. The load–displacement curves of the nanoindentation experiments of NiAlTa metal are shown in Fig. 1 j. The inset illustrates the micro–Vickers hardness of the NiAlTa metal and cBN particle. Parameters derived from the nanoindentation experiments related to the wear characteristics of the material are listed in the table. The nanoindentation data for cBN ceramic particles are obtained from the literature [ 22 ]. The micro–Vickers hardness and nanoindentation data show that cBN particles have much higher (nano)hardness and elastic modulus than NiAlTa metals. Notably, the addition of Ta atoms substantially increases the hardness of the β–NiAl phase. This is related to the dispersion–strengthening effect of the nanoparticles and the solid–solution strengthening effect of the Ta atoms. According to the classical Archard's law [ 23 ], the increase in hardness improves the wear resistance of the material. The high hardness and elastic modulus confer high resistance to mechanical degradation and failure of cBN particles. The H / E r ratio indicates the penetration depth that a material can withstand without exceeding its elastic limit. A high H / E r ratio is desirable because it implies that the material has a long “elastic strain failure” time to allow the applied load to be redistributed over a large area without strain localization. Also, a high H / E r ratio indicates that there are few roughness peaks on the wear surface where the force exceeds its elastic limit, which may lead to a reduction in the coefficient of friction [ 24 ]. The high H / E r ratio implies that cBN particles have excellent wear resistance and a low coefficient of friction. Another parameter related to wear characteristics is H 3 / E r 2 , which indicates the ability of a material to resist plastic deformation in loaded contact, namely the yield strength [ 25 ]. A ratio two orders of magnitude larger indicates that cBN particles have a better ability to resist plastic deformation. In addition, the elastic recovery rate η is also related to the wear characteristics of metallic materials. η is defined as the ratio of the elastic deformation energy ( E elastic ) to the total deformation energy ( E total ) during the loading–unloading process [ 24 , 26 ]. The elastic recovery rate reflects the cracking resistance of the material. The total deformation energy during loading is represented by the area under the loading curve ( L ) from the surface to the maximum depth of indentation ( h max ) ( S 1 + S 2 ). The elastic deformation energy during unloading is represented by the area under the unloading curve ( L ′) between the final indentation depth ( h f ) and the maximum indentation depth ( h max ) ( S 2 ). The high elastic recovery rate suggests that cBN particles have better crack resistance than NiAlTa metals. This is unexpected. Friction and Wear Studies. The friction and wear experimental principle is demonstrated in Fig. 2 a. Under a specific load, speed, and displacement, the upper specimen ball remains relatively stationary and the lower specimen plate reciprocates to achieve sliding wear. The real–time coefficient of friction (COF) curves of NiAlTa/cBN composites sliding against ZrO 2 ceramic balls at different temperatures and loads are shown in Fig. 2 b and Fig. 2 c, respectively. With the increase of normal loads or temperatures, the COFs of NiAlTa/cBN composites show a decreasing or increasing trend. However, the COFs do not show a strict negative or positive correlation with loads or temperatures. The variation in the COFs indicates that the NiAlTa/cBN composites undergo different wear mechanisms under different experimental conditions. This may be related to the evolution of the microstructure and chemical composition of the tribo–layers and subsurfaces or the real contact state between the friction pairs. It is noteworthy that compared with the pure NiAlTa metallic material, the COF is reduced by half when micron–sized cBN particles are added [ 27 ]. This may be attributed to the “friction reduction” effect of cBN particles and local chemical composition fluctuations. In particular, compared with the conventional phenomenon, an abnormal increase in COF with increasing temperature is observed in this system. This result is related to the complex interaction of temperature and load that affects the evolution of the wear products or tribo–layers. The real–time COF curve is an important reflection of the “formation–breakdown–reorganization” process of the tribo–layer. From Fig. 2 b and Fig. 2 c, it can be found that the real–time COF curves are divided into two stages, namely, the running–in stage (fragmentation and compaction of wear debris) and the stabilization stage (rupture–reorganization stage). Changes in thermal–contact stresses in localized areas may lead to the breakdown of the tribo–layer. Cracks or spalling pits may develop within the tribo–layer due to fretting wear under cyclic stresses [ 13 ]. Fluctuating real–time COFs reflect this. The average wear rates of NiAlTa/cBN composites at different temperatures and loads are displayed in Fig. 2 d. The average wear rate of NiAlTa/cBN composites is negatively correlated with load and positively correlated with temperature. At 25 ℃, the average wear rate of NiAlTa/cBN composites reaches a minimum value (4.25 × 10 –7 mm 3 ·N –1 ·m –1 ). The large slope indicates a high–temperature sensitivity of the wear rate of NiAlTa/cBN composites. This may be related to the tribo–induced microstructure and chemical composition of the tribo–layers and subsurfaces of the cBN particles and NiAlTa metal. Figure 2 e shows a plot of the average wear rate of NiAlTa/cBN composites of SPS compared with the conventional composites obtained with different processes or techniques. Compared with the conventional composites, the NiAlTa/cBN composites have lower wear rates over a wide temperature range, which indicates that the NiAlTa/cBN composites exhibit excellent wear resistance. The ultra–low wear rate at room temperature is observed. This is one of the lowest wear rates reported so far. The excellent wide temperature range wear resistance is attributed to the composition and structural design of the composite. On the one hand, it is attributed to the composition of the composites. The soft–hard combination of β–NiAl–(Ni, Al)Ta has good resistance to high–temperature softening and strain hardening induced by heterogeneous deformation [ 28 ], preventing the occurrence of failure behaviors such as cBN particles being pulled out. The soft–hard combination of β–NiAl–(Ni, Al)Ta can effectively coordinate the local deformation and distribute the elastic–plastic strain at high temperatures to inhibit the crack initiation and extension. On the other hand, it is attributed to the structural design of the composites. The micrometer cBN particles with high hardness and high elastic modulus provide good load support and stress transfer, which retard the increase of the true contact area. Meanwhile, NiAlTa metal with multiple deformation pathways disperses the stresses in cBN particles and allows NiAlTa/cBN composites to undergo synergistic deformation without damage. These are proven in the subsequent sections. Wear Mechanism. To elucidate the effect of load and temperature on the wear mechanism of NiAlTa/cBN composites, typical macroscopic wear morphology is presented in Fig. 3 . Figure 3 a shows the macroscopic wear morphology of NiAlTa/cBN composites at 25 ℃ and 100 N. The lower left inset illustrates the wear morphology of a paired ZrO 2 ceramic ball. At low temperatures and high loads, the NiAlTa metal experiences only a mild plastic deformation. The pulling out of cBN particles is not observed. The shear stress δ xz calculated based on the Hamilton model is a powerful tool to evaluate the elastic or plastic behavior of composites under friction loading [ 29 ]. The calculated shear stress ( δ xz ) field in the subsurface of NiAlTa metal and cBN particles based on the Hamilton model is displayed in Fig. 3 b. The calculated shear stress shows a gradient distribution along the depth below the sliding surface. At the beginning of the sliding contact, the shear stress values in the NiAlTa metal (635 MPa) are slightly higher than those in the cBN particles (610 MPa). However, all these shear stress values are much smaller than the yield strength of NiAlTa metal (~ 1200 MPa) [ 4 ] and the compressive strength of cBN particles (~ 38000 MPa) [ 22 ]. Both NiAlTa metal and cBN particles are within the elastic deformation range under friction loading. The ultra–low wear rate suggests that NiAlTa/cBN composites may be nearly wear–free at low temperatures and high loads through the anti–friction and anti–wear effect of the tribo–layer or the structural stability that resists strain localization. In addition, dislocation motion within the metal and ceramic may not be easily triggered during sliding wear. However, strain localization or cracking can still occur in the topmost layer of the material due to the introduction of a large number of defects, leading to damage or roughening of the surface [ 18 ]. This is hard to avoid. Under the indentation of paired microconvexes, grooves are found as a typical feature of abrasive wear on the wear surfaces of NiAlTa metals, cBN particles, and ZrO 2 ceramic balls. Grooves are caused by two– or three–body abrasive wear resulting from wear particles generated and retained between the two surfaces during repeated sliding process. In addition, the large hardness difference between NiAlTa metal and cBN ceramic particles causes NiAlTa metal to be preferentially worn in dry sliding wear. This is confirmed by the height difference at the metal/ceramic particle interface illustrated in the upper right inset. The protruding cBN particles bear the majority of the stress in the subsequent sliding wear. This may be one of the reasons why NiAlTa/cBN composites have the lowest wear rate at room temperature. Figure 3 c and Fig. 3 d show the macroscopic wear morphology of NiAlTa/cBN composites at 1000 ℃ for 10 N and 100 N, respectively. The lower left inset exhibits the wear morphology of the paired ZrO 2 ceramic ball. The reduction of the strength of the ZrO 2 ceramic balls due to the high temperature leads to severe wear at both low and high loads (corresponding to large diameters). The increase in the contact area between the friction pairs reduces the wear rate by decreasing the contact stress. The ZrO 2 wear debris generated by the wear can be captured in the wear scars and is strongly involved in the subsequent sliding process. The number of grooves parallel to the sliding direction is significantly reduced, indicating that sliding–induced abrasive wear is avoided. In addition, white–green paste–like substances are found on the worn surfaces. The higher normal load results in a more homogeneous distribution of the paste–like substance. The Raman spectra of the upper right inset in Fig. 3 e show that the white–green paste–like substance is a mixture of ZrO 2 and Ta 2 O 5 . This could be the reason why the coefficient of friction is halved when micron–sized cBN particles are added. In addition, the bright tribo–layer is found, which is attributed to the friction heat and the poor thermal conductivity of the oxidized particle layer. Figure 4 a, Fig. 4 b, and Fig. 4 c show the microscopic wear morphology of NiAlTa/cBN composites at 25 ℃ and 100 N, 1000 ℃ and 10 N, and 1000 ℃ and 100 N, respectively. Besides the features observed in the macroscopic morphology, tribo–induced tribo–layers and cracking or spalling of the cBN particles under high loads or high temperatures are found. The presence of cracks in the tribo–layer tends to make the tribo–layer delaminated. At high temperatures, fine wear debris is observed, which is a typical feature of oxidative wear [ 8 ]. The generation of fine wear debris is a prerequisite for the formation of the tribo–layer. EDS analysis reveals that the tribo–layer on the NiAlTa metal surface is enriched with elements such as B, O, and Zr. The worn cBN particle surface is enriched with the element O (Fig. 4 d). This indicates that tribo–or high–temperature–induced chemical mixing or reaction is significantly triggered on the NiAlTa metal and cBN particle surfaces. The cracking or spalling of cBN particles is closely related to the changes in their fracture toughness. The inset of Fig. 4 c shows the indentation fracture toughness ( K IC ) and microhardness of cBN particles before and after wear. The fracture toughness ( K IC ) was calculated by using Shetty's equation [ 1 , 30 ]. Where K IC is the indentation fracture toughness; P is the indentation load; a is half of the indentation size; and l is the crack length measured from the indentation corner. The fracture toughness measurement obtained in this way does not represent the true fracture toughness of cBN. However, the measurements can qualitatively characterize the effect of chemical changes on the cBN particle surface on its hardness and fracture toughness before and after sliding wear [ 1 ]. Compared with the cBN particles before the experiment (8.51 MPa·m 1/2 and 6082 HV), the cBN particles after sliding wear exhibit high hardness and low K IC (4.49 MPa·m 1/2 and 8088 HV). This indicates that the cBN particles become hard and brittle after high–temperature sliding wear due to changes in surface chemical composition. Therefore, it is reasonable to assume that the formation of oxides on the particle surface increases the tendency of crack nucleation and destroys the integrity of the ceramic particles during sliding. This is in contrast to the toughening effect of TiC particles due to surface chemical changes. Raman spectra of the cBN particle surface show that besides the scattering peaks of non–stoichiometric cBN 1–x and B, high–temperature–induced B 2 O 3 is detected (Fig. 4 e). Figure 4 i demonstrates the oxidation process of cBN 1–x particles at high temperatures. The high concentration of vacancies present in the non–stoichiometric cBN 1–x particles is occupied by O or N atoms from the air. After the desorption of O or N atoms occurs, the cBN 1–x particles react with O 2 to produce B 2 O 3 and release N 2 [ 21 ]. During the oxidation process, cBN 1–x particles may crack due to internal stress release or cleaving effect [ 21 ]. This may also be the cause of the cracking of cBN particles. B 2 O 3 can exist in a crystal or amorphous state. The atomic model of crystalline B 2 O 3 is shown in the inset. The low melting point of B 2 O 3 (~ 450 ℃) in a liquid state at 1000 ℃ reduces the coefficient of friction and wear rate. Figure 4 f shows the Raman spectra of the tribo–layer on the NiAlTa metal surface. Raman spectra suggest that the tribo–layer consists of ZrO 2 , Ta 2 O 5 , Al 2 O 3 , and NiO oxides. In room–temperature sliding wear, the tribo–oxidation process is promoted by deformation heat, friction heat, and increasing particle energy [ 31 ]. When the wear debris particles are extremely fine, the fine metal particles may be completely oxidized spontaneously under certain conditions [ 32 ]. Thus, oxides are produced even at room temperature. The weak and broad peaks of the oxides are observed, which indicates a low amount of oxides and a high degree of amorphization in the tribo–layer. In high–temperature sliding wear, the Raman spectra with high number and strong scattering peaks imply that ZrO 2 and Ta 2 O 5 are the main constituents of the tribo–layer. In addition, it is noteworthy that the scattering peaks of Ta 3 N 5 are detected at 1000 ℃, which suggests that the Ta element may have a tribo–chemical reaction with the cBN particles. Figure 4 g illustrates the ionic potential and melting point of the oxides in the friction pair. Hard or lubricant oxides classified according to crystal–chemical theory also play an important influence on the transformation of the wear mechanism in high–temperature sliding wear. According to the crystal–chemical theory, oxides with high ionic potential ( φ = Z / r , Z is the cation charge and r is the cation radius)) have excellent lubricating and anti–wear properties [ 33 ]. Therefore, B 2 O 3 ( φ = 12) and Ta 2 O 5 ( φ = 7.8) as lubricant oxides may reduce the coefficient of friction and wear rate of the composites. In high–temperature sliding wear, the tribo–layer is formed by repeated fragmentation, compaction, and sintering of oxide wear debris [ 11 ]. The wear debris, as the basic unit that makes up the tribo–layer, reduces the COF or wear rate by eliminating the contact between the friction pairs, increasing the surface hardness, or generating lubrication products. Our previous studies showed that when ZrO 2 ceramic balls are used as high–temperature sliding pair, wear–induced ZrO 2 wear debris usually serves as the main constituent of the tribo–layer (> 70%). This is consistent with the results observed in this study. When this tribo–layer slid against the paired ZrO 2 ceramic balls, a high COF was caused due to the high similarity (e.g., similar physical/chemical properties, lattice parameters) between the friction pairs [ 27 ]. Here, when high normal loads are applied (more and large sized ZrO 2 wear debris is generated), ZrO 2 wear debris exceeding the critical wear debris size is removed from the wear scar without participating in the formation of the tribo–layer at a constant temperature. At this point, according to the crystal–chemical theory, the high–temperature–induced generation of oxides with high ionic potentials (e.g., Ta 2 O 5 , B 2 O 3 ) of the metal or cBN particles is the main reason for the reduction in the COF and wear rate. Temperature usually affects the evolution of the tribo–layer by influencing the oxidation rate, the mechanical deformation mode, and the wear debris sintering rate. The formation of the tribo–layer depends on the sensitivity to tribo–chemical reactions of the internal structure or elements of the alloy matrix [ 34 ]. Here, when high temperatures are applied, the formation of an Al 2 O 3 protective film from the selective oxidation of Al greatly slows down the oxidation rate of NiAlTa metals. That is, the oxidation products of the metal are not sufficient to control the formation of the tribo–layer. However, the increasing adhesion force between the wear debris due to high temperature leads to the participation of large size and quantity of ZrO 2 wear debris in the subsequent sliding wear and dominates the formation of the tribo–layer [ 32 ]. As a result, a high COF is caused. In addition, high melting point oxides such as ZrO 2 (2680 ℃), NiO (1987 ℃), and Al 2 O 3 (2040 ℃) endow the tribo–layer with high hardness, leading to a low wear rate. The formation rate and coverage of the tribo–layer increase with increasing temperature. The direct contact between the friction pairs is reduced and the wear rate is lowered. At atmospheric pressure, the cBN → hBN phase transition usually occurs in the temperature range > 1500 ℃ [ 35 ]. Interestingly, the tribo–induced cBN → hBN phase transition is observed in sliding wear experiments at 1000 ℃. The possible reasons for this are as follows: Firstly, in high–temperature sliding wear, after some of the exfoliated cBN particles are repeatedly fragmented to submicron size, the phase transition temperature is significantly lowered, which makes the cBN → hBN phase transition possible at 1000 ℃. Secondly, under cyclic stress, high–temperature or tribo–induced mechanical mixing of B 2 O 3 with cBN particles promotes the cBN → hBN phase transition [ 35 ]. The sublimation pits on the cBN particle surface and the Raman scattering peaks of hBN demonstrated in Fig. 4 h both confirm the occurrence of the phase transition. In this experiment, the cBN → hBN phase transition may proceed through the solid–state transformation mechanism (cBN → rBN → hBN) and the CVD mechanism (sublimation and formation of single–atom SP 2 bonds on the cBN particle surface) [ 35 ]. The phase transition mechanism is summarized in Fig. 4 h. The sublimation pits observed on the cBN particle surface confirm the existence of the CVD mechanism. Evidence for the solid–state transformation mechanism is provided in the next section. The generation of phase–transition induced hBN contributes to the reduction of the COF and wear rate of NiAlTa/cBN composites. Evolution of Tribo–induced Tribo–layers and Plastic Deformation Layers With Nano–heterostructures. The tribo–layer with nano–heterostructures induced by sliding wear controls the friction and wear process as it is where the friction energy is dissipated and accommodates stress, speed, and temperature gradients. High–resolution FIB/TEM was used to characterize the fine microstructure and chemical composition of the tribo–layer formed in the room and high–temperature sliding wear. The results are shown in Fig. 5 . The tribo–layers on the NiAlTa metal and cBN particle surfaces were observed separately. Figure 5 a and Fig. 5 b show the tribo–layers on the NiAlTa metal and cBN particle surfaces at room temperature, respectively. The microscopic morphology of the tribo–layer on the NiAlTa metal surface is illustrated in Fig. 5a 1 . The tribo–layer with a thickness of about 25 nm is found. EDS analysis shows that the tribo–layer consists of O, Al, Ni, Zr, and Ta elements. A high density of dislocations is observed in the subsurface, accompanied by the appearance of dislocation tangles. High–resolution TEM photograph, fast fourier transform map (FFT map), and inverse fast fourier transform map (IFFT map) of the tribo–layer are shown in Fig. 5a 2 . The tribo–layer is characterized by a disordered amorphous state. This is confirmed by the diffraction halo in the FFT map. The IFFT map indicates the presence of a large number of dislocations in the β–NiAl phase. It is noteworthy that the β–NiAl phase does not undergo dislocation–mediated grain refinement, which serves as one of the typical sub–surface microstructural responses in sliding wear. This implies that the tribo–layer accommodates the plastic deformation induced by sliding wear. Furthermore, the lattice strain ( ε xy ) map of Fig. 5a 2 obtained by geometrical phase analysis (GPA) suggests the presence of severe lattice distortion within the tribo–layer (Fig. 5 a 3 ). Therefore, it is reasonable to infer that the amorphization of the tribo–layer on the NiAlTa metal surface is attributed to the plastic deformation–induced solid–state amorphization process. Reciprocating sliding leads to an increase in the number of dislocation boundaries and the free energy of the system [ 36 ]. The high density of dislocations and other defects are concentrated in nano–sized wear debris (e.g., ZrO 2 , Al 2 O 3 ). When the free energy reaches a critical value, the lattice of the nanograins at the critical size collapses to release the elastic strain energy due to the lack of interatomic coordination. Structural disorder is introduced at the nanograin boundaries [ 36 ]. In the subsequent sliding process, the amorphization gradually extends to the entire tribo–layer. The doping of small–sized O atoms accelerates the formation of amorphous products by altering the atomic coordination through directional bond contributions and large negative mixing enthalpies [ 37 ]. Oxygen further weakens the lattice rigidity and makes the amorphous region easy to extend [ 36 ]. Figure 5b 1 demonstrates the microscopic morphology and EDS mapping of the tribo–layer on the cBN particle surface. Cracks perpendicular to the sliding direction are found. Amorphous substances with a similar chemical composition to the tribo–layer in Fig. 5a 1 fill the cracks. This reconfirms that the amorphous tribo–layer on the NiAlTa metal surface accommodates plastic strains well. A magnification of the tribo–layer on the cBN particle surface is shown in Fig. 5b 2 . The tribo–layer with a thickness of about 30 nm is found. EDS analysis suggests that the tribo–layer is composed of the elements O, N, and Ta. Elliptical nanoparticles are distributed on the tribo–layer surface. High–resolution TEM photograph and FFT map indicate that the elliptical particles are Ta 3 N 5 . The high–hardness Ta 3 N 5 particles can play the roles of load support and dispersion of contact stress. High–resolution TEM photograph and FFT map of the tribo–layer indicate that the tribo–layer on the cBN particle surface also exhibits amorphous characteristics (Fig. 5 b 3 ). Raman spectra in the inset confirm the presence of Ta 3 N 5 and Ta–O–N amorphous. The GPA map shows that a large number of defects (e.g., dislocations and vacancies) are found within the tribo–layer and subsurface of the cBN particles (Fig. 5 b 4 ). In addition, in the cracks, localized atomic disorder regions are observed to appear along the nanograin boundaries (Fig. 5 b 5 ). This is a transitional stage of amorphization. The discovery of this evidence directly confirms the existence of the solid–state amorphization process. In addition, the presence of Ta 2 B and Ta 3 N 5 nanoparticles suggests that a chemical reaction between Ta and cBN occurs. Figure 5 b 6 shows the atomic schematic of TaN and TaB 2 produced by the chemical reaction of Ta with cBN. TaN is formed through a diffusion reaction between Ta and cBN. This phenomenon is commonly found in high–energy ball milling or mechanical grinding [ 38 ]. The amorphization of the tribo–layer on the cBN particle surface is attributed to the significant lattice distortion triggered by the doping of O atoms into the face–centered cubic structure of the TaN lattice. This is similar to the amorphization process of Ta–O–N in reactive sputtering [ 39 ]. The above results indicate that the amorphous tribo–layer on the NiAlTa metal and cBN particle surfaces at room temperature seems to be the main reason for the low COF and wear rate of NiAlTa/cBN composites. Figure 5 c and Fig. 5 d show the tribo–layer on the NiAlTa metal and cBN particle surfaces at high temperatures, respectively. The microscopic morphology and EDS mapping of the tribo–layer on the NiAlTa metal surface are demonstrated in Fig. 5c 1 . The tribo–layer consisting of nanoparticles is found. EDS analysis shows that the tribo–layer is enriched with Zr elements. According to the Hall–Petch relationship, the tribo–layer composed of nanoparticles exhibits high hardness [ 40 ]. This is favorable for wear resistance. The subsurface is enriched with element O, which suggests that the elements in the subsurface may be oxidized. A large number of holes and cracks are found within the tribo–layer and subsurface. The large number of grain boundaries and defects such as holes or cracks within the tribo–layer act as O internal diffusion channels. Also, nonequilibrium structures (e.g., vacancies, dislocations, and lattice distortions) in the tribo–layer provide a pathway for the internal diffusion of oxygen atoms [ 31 ]. Tribo–induced high vacancy concentration tends to trigger the generation of micro-voids in the oxide layer, which makes the oxide layer loose and poorly protected. The presence of holes and cracks significantly weakens the bonding strength of the tribo–layer. It is also noteworthy that the cracks are almost perpendicular to the wear surface. A magnified view of the tribo–layer surfaces is shown in Fig. 5c 2 . Ta 3 N 5 nanoparticles are uniformly distributed on the tribo–layer surface. The Raman spectra shown in the inset confirm the presence of Ta 3 N 5 particles. Ta 3 N 5 particles are not observed on the tribo–layer surface of the NiAlTa metal surface at room temperature. A localized magnified view of Fig. 5c 1 is shown in Fig. 5c 3 . A large number of holes and cracks extending along grain boundaries are found. Notably, the grains in the subsurface are significantly refined. In addition, numerous distortions and mismatched dislocations are present on the grain boundaries in the ZrO 2 surface layer, which act as dislocation pinning points to hinder dislocation climbing and slipping and strengthen the ZrO 2 surface layer [ 34 ]. The β–NiAl–(Ni, Al)Ta structure undergoes degradation at high temperatures and high strains. This is caused by large contact loads at high temperatures. The polycrystalline diffraction rings of the labeled region in Fig. 5c 3 are shown in Fig. 5c 4 and Fig. 5c 5 . The polycrystalline diffraction ring shows that the tribo–layer consists of ZrO 2 . The subsurface is composed of NiO, Al 2 O 3 , and Ta 2 O 5 . These grains do not display significant texturing, as evidenced by the relatively uniform intensity of the diffraction ring. Figure 5 c 6 demonstrates high–resolution TEM photographs, local magnification, and FFT maps of the nanoparticles in the subsurfaces. All these results indicate that plenty of stacking faults and deformation twins exist within the subsurface. When the grain size decreases to tens of nanometers, the deformation is no longer controlled by normal slip but by partial dislocation activity, which predisposes to the formation of twins and stacking faults (SFs) [ 41 ]. SFs can evolve into a source of stimulated dislocation multiplication. Meanwhile, deformed twins (DTs) hinder dislocation motion. Progressive and stable strengthening of subsurfaces is achieved [ 34 ]. Therefore, the high density of SFs and DTs–mediated stabilized plastic deformation may be the reason for the excellent high–temperature wear resistance and load–bearing capacity of NiAlTa/cBN composites compared with other composites. In dry sliding wear, the huge hardness difference between metal and ceramic particles causes the metal to be worn preferentially. The cBN particles act as the main load–bearing region. Concave areas such as NiAlTa metal areas serve as non–load bearing areas, which act as “collectors” for wear debris such as ZrO 2 . The “collector” is also transformed into a load–bearing region under stress and temperature, namely the ZrO 2 surface layer. After the formation of the hard ZrO 2 surface layer, the contact between the ZrO 2 surface layer and the ZrO 2 ceramic ball is mainly elastic. The wear rate of NiAlTa/cBN composites should supposedly be reduced, but this is not the case. Here, the subsurface controls the wear behavior of NiAlTa/cBN composites. The subsurface fine–crystalline layer is triggered by plastic deformation mediated by a combination of dislocations, faults, or deformation twins. The subsurface fine–crystalline layer does not directly participate in the sliding process, but only serves as a load–bearing layer for the ZrO 2 surface layer. Considering the high strength of the ZrO 2 surface layer, the plastic deformation does not always start from the surface layer. Due to the gradient distribution of applied stress under the Hertzian contact, plastic deformation or strain localization within the subsurface layer occurs when the local stress exceeds the elastic limit of the subsurface material [ 41 ]. The continuous accumulation of plastic strain makes the fine–crystalline layer unstable and prone to cracks or holes at the metal/ceramic interface or grain boundaries at a certain depth below the contact surface. As observed in Fig. 5c 1 and Fig. 5c 3 . The oxidation of the elements aggravates the subsurface instability. The delamination wear due to strain localization is likely to be the main reason for the increased wear rate of NiAlTa/cBN composites at high temperatures. TKD Analysis of Tribo–layers and Plastic Deformation Layers With Nano–heterostructures. Compared with conventional electron backscatter diffraction (EBSD), the coaxial transmission kikuchi diffraction (TKD) technique offers a significantly improved pattern quality and resolution. To obtain the grain orientation, local misorientation, and recrystallization information of the tribo–layer and subsurface, the tribo–layer and subsurface of NiAlTa/cBN composites were analyzed by the TKD technique. Some regions could not be identified by TKD, which could be attributed to small grain size or amorphization. Figure 6 a and Fig. 6 b show the tribo–layers and sub–surfaces of NiAlTa metal and cBN particle surfaces at room temperature, respectively. Figure 6 a 1 , Fig. 6a 2 , and Fig. 6a 3 display the inverse pole Figureure (IPF map), local misorientation map (KAM map), and recrystallization map of the tribo–layer of NiAlTa metal, respectively. The amorphous tribo–layer is difficult to be analyzed because it cannot produce Kikuchi patterns. The crystal orientation of the β–NiAl phase in the subsurface changes slightly. This indicates that the small friction shear strain causes a mild plastic deformation of the subsurface. This again demonstrates that the amorphous tribo–layer on the surface adapts to the elastic–plastic deformation induced by sliding wear. Low angle grain boundaries (LAGBs) are found (Fig. 6 a 1 ), which evolve from dislocation walls formed by the accumulation and rearrangement of dislocations [ 34 ]. Geometrically necessary dislocations (GNDs) are generated to accommodate subsurface shear deformation. In addition, GNDs show high density at grain boundaries (Fig. 6 a 2 ). This suggests that the deformation difference between the soft and hard phases of β–NiAl–(Ni, Al)Ta leads to a high density of GNDs at the interfaces, which significantly enhances the strain–hardening ability of NiAlTa metals (heterogeneous deformation–induced strain–hardening) [ 28 ]. Accumulated GNDs can induce strain distribution between soft and hard phases to accommodate elastic–plastic deformation due to dynamic loading [ 28 ]. Substrucured and deformed grains are found within the subsurface (Fig. 6 a 3 ). Figure 6b 1 and Fig. 6b 2 show the IPF and KAM maps of the tribo–layer of cBN particles, respectively. The orientation changes around the cracks. Ta 3 N 5 nanoparticles on the surface of the amorphous tribo–layer exhibit random orientations. GNDs show high density in Ta 3 N 5 nanoparticles and around cracks. This suggests that Ta 3 N 5 particles play a load–supporting and stress–transferring role in sliding wear. The presence of strain gradients requires the storage of GNDs to maintain deformation compatibility. Compared with metals, dislocation movement in ceramics is inherently retarded, which is attributed to strong ionic and covalent bonding [ 42 ]. Therefore, high density GNDs are only found around cracks. Under high friction loads, the retardation of dislocation movement is highly susceptible to cracking of ceramic particles. Figure 6 c and Fig. 6 d show the tribo–layers and subsurfaces of NiAlTa metal and cBN particles at high temperatures, respectively. Figure 6 c 1 , Fig. 6c 2 , and Fig. 6c 3 demonstrate the IPF map, KAM map, and recrystallization map of the tribo–layer of NiAlTa metal, respectively. The oxide grains within the ZrO 2 surface layer and the subsurface both show random orientations. The random grain orientation makes the grain boundary energy barrier high, which can effectively hinder the crack extension. However, due to the minimal strain tolerance and high hardness, the ZrO 2 surface layer also ruptures or breaks to eliminate plastic deformation energy in sliding wear. Severe dislocation–mediated plastic deformation occurs in the subsurface, which is confirmed by plenty of high–angle grain boundaries (HAGBs) and LAGBs. Severe plastic deformation (SPD) usually leads to crack nucleation. This is because the maximum tensile stress is at the outer surface of the actual contact area (at the trailing edge of the contact). Also, according to the Hamilton model of subsurface stresses under spherical contact, friction force shifts the maximum shear stress in the contact region towards the wear surface [ 29 ]. The initial direction of crack extension is perpendicular to the wear surface driven by the maximum tensile stress. This is consistent with the observation in Fig. 6c 1 . The average size of grains in the ZrO 2 surface layer is 100 nm. The grain size within the subsurface shows a gradient distribution (50 nm → 220 nm) (Fig. 6 c 1 ). The lack of dislocation sources inside the small grains, as well as the limited storage of dislocations inside the grains due to their small size, deprives the subsurface of strain–hardening capacity. The strain–hardening capacity is critical for maintaining the off–domain plastic strain. The few dislocations in the subsurface prove this (Fig. 6 c 2 ). In addition, due to the lack of a transition layer, the large size difference between the ZrO 2 surface layer and the nanogradient layer in the subsurface inevitably causes delamination due to the concentration of friction stress. In high–temperature sliding wear, the decrease in the stability of the subsurface leads to the delamination and peeling of the tribo–layer resulting in a high wear rate. This is confirmed by the above evidence. In addition, heat and flow stress gradients lead to the formation of dislocation–mediated ultrafine crystalline layers presenting a nanogradient structure. The grain refinement at the subsurface is mainly determined by dislocation activity. Dislocation entanglements are gradually transformed into LAGBs. Under the effect of plastic strain, relative sliding and rotation between the sub–grains are generated, and eventually a gradient fine–grained layer with HAGBs is formed. However, the continuous accumulation of plastic strain causes strain localization in the fine–grain layer, which is prone to cracking at the metal/ceramic interface or defects in the subsurface. In contrast to the subsurface, high density GNDs are found within the ZrO 2 surface layer (Fig. 6 c 2 ). The density of GNDs is proportional to the strain gradient, which indicates a high strain near the surface. A large number of deformed grains are found within the ZrO 2 surface layer (Fig. 6 c 3 ). Besides deformed grains, recrystallized grains are found within the subsurface. Recrystallized grains are first nucleated in deformation bands with high deformation storage energy distributed densely at dislocations and subgrain boundaries [ 43 ]. Subgrains in the deformation zones grow to become effective nuclei for recrystallization by consuming the surrounding high–energy zone. The high temperature significantly accelerates the nucleation rate of dynamically recrystallized grains. Figure 6 d 1 and Fig. 6d 2 show the IPF and KAM maps of the tribo–layer of cBN particles, respectively. The subsurface of cBN particles undergoes a mild orientation change. When the critical shear stress approaches the theoretical shear of cBN particles, a local loss of lattice stability occurs. Dislocations begin to homogeneously or heterogeneously nucleate and microplastic deformation occurs [ 22 ]. Meanwhile, at high stresses, the cBN particles undergo the FCC → HCP phase transition, which is essential to maintain the stable microplasticity of the ceramic particles. CONCLUSIONS NiAlTa/cBN composites exhibit excellent wear resistance, which is attributed to the specific tribo–layers with special nano–heterostructures induced by stress and temperature. At room temperature, the extremely low wear rate and low COF of the composites are attributed to the formation of an amorphous tribo–layer. The nanograins undergo solid–state amorphization induced by plastic deformation. O and Zr atoms promote the amorphization process. At high temperatures, strain localization of the oxide fine–crystalline layer with nanogradient structure increases the wear rate of the composites. Meanwhile, the tribo–induced amorphous oxide layer and oxidative cleaving effect decrease the fracture toughness of cBN particles and increase the wear rate. Tribo–induced phase transition of cBN particles (fccBN → hcpBN) and tribo–chemical reaction of Ta with cBN are observed. Ta 3 N 5 nanoparticles generated by tribo–chemical reaction play a load–supporting and stress–transferring role in sliding wear. In addition, dislocations, faults networks, and the FCC → HCP phase transition synergistically improve the strain–hardening ability of cBN particles and reduce the wear rate. In conclusion, the intrinsic structure of NiAlTa/cBN composites relies on multiple deformation pathways of NiAlTa metals and cBN ceramics to induce tribo–layers with specific nano–heterostructures, thus adapting to the gradient elastic–plastic strain distributed along the friction interface to achieve excellent wear resistance. EXPERIMENTAL SECTION/METHODS Composites preparation. Ni–coated cBN particles with a weight ratio of 25% were added to NiAlTa alloy powder (45Ni–45Al–10Ta, at%). NiAlTa/cBN composite blocks (Φ = 30 mm, h = 10 mm) were prepared by spark plasma sintering (1280°C, 50 MPa, and 30 min) after ball milling (300 rpm/min and 4 h). Several rectangles (30 × 10 × 4 mm) were removed from the NiAlTa/cBN composite block by a diamond wire saw. The rectangles were grinded with diamond disks; then they were polished with Al 2 O 3 polishing paste; finally, the polished samples were ultrasonically cleaned in alcohol. Sliding wear experiments. Dry sliding wear experiments were conducted by an MTF–5000 tribometer (Rtec, USA) equipped with a ball–on–plate reciprocating module. The plate was the NiAlTa/cBN composite. The ball was a ZrO 2 ceramic ball (Φ = 9.525 mm). The reason for choosing ZrO 2 ceramic balls is to simulate the ZrO 2 ceramic–based abradable coating on the turbine case surface, which rubs against the turbine blades or blade tip protective coating. Speed and displacement were fixed. Temperature and load were used as independent variables to investigate the dry sliding wear behavior of NiAlTa/cBN composites (Temperature 25 ℃, 500 ℃, and 1000 ℃; Load 10 N, 50 N, and 100 N; Sliding speed 0.02 m/s; Time 3600 s; Displacement 10 mm). The experimental temperature is slightly higher than the nominal experimental temperature due to friction heat generation [ 1 ]. Each set of experiments was repeated three times. Characterization methods. The wear morphology and elemental composition of NiAlTa/cBN composites were analyzed by a MIRA3 field emission scanning electron microscope (SEM, TESCAN) equipped with an Ultim MaxN silicon drift type energy dispersive spectrometer (EDS). A D/Max–2500PC X–ray diffractometer (XRD, Cu Kα, 5 °/min, 20°~90°) and a field emission transmission electron microscope (TEM, Thermofisher Talos F200X) were utilized to determine the phase composition of the composites. The distribution of cBN particles in the composites was characterized by a microscopic computed tomography (CT). The CT data was processed using AVIZO software. The (nano)hardness and elastic modulus of the composites were determined by a TIME6610AT digital microhardness tester (Beijing Times Peak Science and Technology Co., Ltd., China, load 0.5 N) and a nanoindenter (Agilent TechnologiesNano Indenter G200, Agilent, USA, indentation depth 1000 nm). The average of five measurements was recorded. The two–dimensional wear profile and three–dimensional wear morphology of the wear scar were obtained by applying a 2300A–R contact profilometer (Harbin Gauge and Sharpening Tools Group Co., Ltd., diamond stylus with a radius of 2 µm, highest resolution of 10 nm) and a VHX–6000 ultra depth–of–field three–dimensional microscope system (OM, Keyence, Japan). The wear rates of the composites under different experimental conditions were calculated according to Eq. 3 [ 8 ]. Where W r is the wear rate, mm 3 ·N –1 ·m –1 ; S is the average cross–sectional area of the wear scar, mm 2 ; d is the length of the wear scar, mm; P is the load, N; and L is the sliding distance, m. The microscopic morphology, dislocations, grain orientation, local misorientation, and recrystallization of the tribo–layers and subsurfaces of the composites were analyzed by a TEM equipped with an EDS and a high–resolution coaxial transmission kikuchi diffraction (TKD, Bruker, with a step size of 10 nm). TEM and TKD samples were prepared using a dual beam focused ion beam (FIB, Thermo Scientific Scios 2). Small–beam cutting and low–voltage cleaning were employed to accurately obtain the intrinsically true structure to avoid crack formation. The FIB sampling direction was parallel to the sliding direction. Pt coating was deposited before FIB sampling to protect the worn surface. TKD data was processed by the HKL Channel 5 software (Oxford). Declarations Conflict of Interest The authors declare no competing interests. Author Contribution Y.S. carried out the experiments and wrote the paper; G.S. and D.D. designed the project and the material; Y.S., X.W., and W.B. conducted data analysis; Y.S. and D.D. designed the project and analyzed the wear mechanism. All authors contributed to the discussion of the results. Acknowledgements This work is financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB 047010204) and the Tribology Science Fund of the State Key Laboratory of Tribology in Advanced Equipment (SKLTKF24B03). Data Availability Statement The data are available on request from the corresponding author. References Lou M et al (2021) Temperature–induced wear transition in ceramic–metal composites. Acta Mater 205:116545 Cheng Q et al (2022) Microstructure evolution and wear mechanism of in situ prepared Ti–TiN cermet layers at high temperature. Compos Part B–Eng 242:110028 Liu YD et al (2021) Microstructural evolution and mechanical properties of NiCrAlYSi + NiAl/cBN abrasive coating coated superalloy during cyclic oxidation. J Mater Sci Technol 71:44–54 Davenport JR et al (2014) Material needs for turbine sealing at high temperature. 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Supplementary Files image1.png GRAPHICAL ABSTRACT Cite Share Download PDF Status: Published Journal Publication published 28 Aug, 2025 Read the published version in Advanced Composites and Hybrid Materials → Version 1 posted Editorial decision: Revision requested 28 May, 2025 Reviews received at journal 27 May, 2025 Reviewers agreed at journal 22 May, 2025 Reviewers agreed at journal 22 May, 2025 Reviews received at journal 21 Apr, 2025 Reviewers agreed at journal 14 Apr, 2025 Reviewers agreed at journal 12 Apr, 2025 Reviewers invited by journal 08 Apr, 2025 Editor assigned by journal 08 Apr, 2025 Submission checks completed at journal 03 Apr, 2025 First submitted to journal 21 Mar, 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. 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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-6275026","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":432724260,"identity":"34637d26-ae5b-4a8c-91f6-a0e302df44db","order_by":0,"name":"Shuai Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0klEQVRIiWNgGAWjYNCCCgkGfmbStJyxYJBsJkkHY1sFg8EBYlXLz0h+9vALm4S98XHutA8MNXYM/LMb8GsxuJFmbizDI5G47TDv5hkMx5IZJO4QsM9AIsFMWkICSAK1MDCwHQCJEHJY+jdpCQOgw5pBWv4RoYXhRo6Z5IcECcYNzEAtjG1EaDE486ZMmuGAROIMkMMS+5J5JG4Qclh7+jbJn//q7Pn7z25m+PDNTo5/BiGHCSQwMPPAOEDFPHjUQgH/AQbGH4SVjYJRMApGwUgGAHnQO79XeQK6AAAAAElFTkSuQmCC","orcid":"","institution":"University of Science and Technology of China","correspondingAuthor":true,"prefix":"","firstName":"Shuai","middleName":"","lastName":"Yang","suffix":""},{"id":432724261,"identity":"0dca8767-4d27-47ad-ac5a-4a74a133e435","order_by":1,"name":"Siyang Gao","email":"","orcid":"","institution":"Institute of Metals Research","correspondingAuthor":false,"prefix":"","firstName":"Siyang","middleName":"","lastName":"Gao","suffix":""},{"id":432724264,"identity":"19b3f9d0-a065-40e0-a64e-c31d0d092ecf","order_by":2,"name":"Weihai Xue","email":"","orcid":"","institution":"Institute of Metals Research","correspondingAuthor":false,"prefix":"","firstName":"Weihai","middleName":"","lastName":"Xue","suffix":""},{"id":432724265,"identity":"1490f31f-bff2-4af3-8509-a7bf974b5d5c","order_by":3,"name":"Bi Wu","email":"","orcid":"","institution":"Institute of Metals Research","correspondingAuthor":false,"prefix":"","firstName":"Bi","middleName":"","lastName":"Wu","suffix":""},{"id":432724266,"identity":"0493bca8-1633-4c77-a116-03e0c5e072dc","order_by":4,"name":"Deli Duan","email":"","orcid":"","institution":"Institute of Metals Research","correspondingAuthor":false,"prefix":"","firstName":"Deli","middleName":"","lastName":"Duan","suffix":""}],"badges":[],"createdAt":"2025-03-21 07:23:12","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6275026/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6275026/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s42114-025-01415-w","type":"published","date":"2025-08-28T15:57:57+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":79339582,"identity":"80e72a1e-8bdf-491e-9fe2-98b03940bfd2","added_by":"auto","created_at":"2025-03-27 08:25:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1842110,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic of the preparation process of NiAlTa/cBN composites, including powder mixing and spark plasma sintering (SPS). The principle of SPS is demonstrated in it; (b) Microscopic morphology of NiAlTa metal powder and Ni–coated cBN particles. The inset shows the size statistic of the metal powder; (c) Microscopic morphology and EDS mapping of a single Ni–coated cBN particle; (d) High–resolution TEM photograph of cBN particles. The inset illustrates the fast fourier transform map (FFT map) and the atomic model of cBN; (e) Microscopic morphology of NiAlTa/cBN composites; (f) TEM photograph and EDS mapping of NiAlTa metal; (g) High–resolution TEM photograph and FFT map at the interface between A and B phases in Figure. b; (h) XRD patterns of NiAlTa/cBN composites; (i) Microscopic computed tomography of NiAlTa/cBN composites; (j) Nanoindentation load–displacement curve of NiAlTa metal. The loading curve (\u003cem\u003eL\u003c/em\u003e), the unloading curve (\u003cem\u003eL\u003c/em\u003eʹ), the area surrounded by the curves (\u003cem\u003eS\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e and \u003cem\u003eS\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e), and the maximum/final indentation depth (\u003cem\u003eh\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e and \u003cem\u003eh\u003c/em\u003e\u003csub\u003ef\u003c/sub\u003e) are labeled in the Figureure. The inset shows the micro–Vickers hardness of NiAlTa metal and cBN particles. The table illustrates the nanoindentation data.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/37055d6bec47003a6cd5db84.png"},{"id":79340176,"identity":"3c911be3-a762-49fb-918d-f8da70ba0c93","added_by":"auto","created_at":"2025-03-27 08:33:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":309531,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic diagram of the principle of reciprocating sliding wear experiment; (b) Real–time coefficient of friction curves at 1000 ℃ at different loads; (c) Real–time coefficient of friction curves at 100 N at different temperatures; (d) Average wear rates of NiAlTa/cBN composites at different temperatures and loads; (e) Plot of the average wear rates of NiAlTa/cBN composites of SPS compared with conventional composites obtained by different processes or techniques.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/36003ee0c3fa71783daad7c4.png"},{"id":79339586,"identity":"3900b171-ccfc-46a4-bec9-a4acabf7dbc9","added_by":"auto","created_at":"2025-03-27 08:25:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1132542,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Macroscopic wear morphology of NiAlTa/cBN composites at 25 ℃ and 100 N. The inset shows the wear morphology of the paired ZrO\u003csub\u003e2\u003c/sub\u003e ceramic ball and the height difference at the metal/ceramic particle interface; (b) Shear stress (\u003cem\u003eδ\u003c/em\u003e\u003csub\u003exz\u003c/sub\u003e) fields in NiAlTa metal and cBN particles calculated based on the Hamilton model; (c) Macroscopic wear morphology of NiAlTa/cBN composites at 1000 ℃ and 10 N. The inset shows the wear morphology of the paired ZrO\u003csub\u003e2\u003c/sub\u003e ceramic ball; (d) Macroscopic wear morphology of NiAlTa/cBN composites at 1000 ℃ and 100 N. The insets show the wear morphology of the paired ZrO\u003csub\u003e2\u003c/sub\u003e ceramic ball and the Raman spectra of the white–green substance in Figures. d and e.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/13108321d094ff007b96930e.png"},{"id":79340178,"identity":"ec0cfa2a-d9eb-4039-a45a-31f3a57ec409","added_by":"auto","created_at":"2025-03-27 08:33:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1066137,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Microscopic wear morphology of NiAlTa/cBN composites at 25 ℃ and 100 N; (b) Microscopic wear morphology of NiAlTa/cBN composites at 1000 ℃ and 10 N; (c) Microscopic wear morphology of NiAlTa/cBN composites at 1000 ℃ and 100 N. The inset shows the indentation fracture toughness of cBN particles before and after wear; (d) Elemental composition of the tribo–layers on the NiAlTa metal and cBN particle surfaces in Figures. a–c; (e) Raman spectra of the cBN particle surface in Figures. a–c. The inset illustrates the atomic model of crystalline B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e; (f) Raman spectra of NiAlTa metal surfaces in Figures. a–c; (g) Ionic potential and the melting point of the oxides in the friction pair; (h) Two formation mechanisms of hBN. Raman spectra confirm the presence of hBN; (i) Physical and chemical reactions on the cBN particle surface in high–temperature sliding wear.\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/13969244df98f688df7b338e.png"},{"id":79339587,"identity":"842880f9-bfa8-4f12-9c1e-df9de9a271f6","added_by":"auto","created_at":"2025-03-27 08:25:12","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":3275753,"visible":true,"origin":"","legend":"\u003cp\u003e(a\u003csub\u003e1\u003c/sub\u003e) Microscopic morphology of the tribo–layer on the NiAlTa metal surface at 25 ℃. FIB sampling direction is parallel to the sliding direction. The table shows the elemental composition of the tribo–layer; (a\u003csub\u003e2\u003c/sub\u003e) High–resolution TEM photographs, FFT maps, and IFFT maps of the tribo–layer on the NiAlTa metal surface; (a\u003csub\u003e3\u003c/sub\u003e) Geometrical phase analysis (GPA) map of Figure. a\u003csub\u003e2\u003c/sub\u003e; (b\u003csub\u003e1\u003c/sub\u003e) Microscopic morphology and EDS mapping of the tribo–layer on the cBN particle surface at 25 ℃; (b\u003csub\u003e2\u003c/sub\u003e) Magnified view of the tribo–layer on the cBN particle surface. The table illustrates the elemental composition of the tribo–layer. High–resolution TEM photograph and FFT map of Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e particles; (b\u003csub\u003e3\u003c/sub\u003e) High–resolution TEM photograph and FFT map of the tribo–layer on the cBN particle surface. The inset demonstrates the Raman spectra of the tribo–layer; (b\u003csub\u003e4\u003c/sub\u003e) Geometric phase analysis (GPA) map of Figure. b\u003csub\u003e3\u003c/sub\u003e; (b\u003csub\u003e5\u003c/sub\u003e) High–resolution TEM photograph within the cracks of cBN particles; (b\u003csub\u003e6\u003c/sub\u003e) Schematic diagram of the tribo–chemical reaction between Ta and cBN; (c\u003csub\u003e1\u003c/sub\u003e) Microscopic morphology and EDS mapping of the tribo–layer on the NiAlTa metal surface at 1000 ℃. The table shows the elemental composition of the tribo–layer; (c\u003csub\u003e2\u003c/sub\u003e) A magnified view of the tribo–layer surface. The inset shows the Raman spectra of the surface nanoparticles; (c\u003csub\u003e3\u003c/sub\u003e) A magnified view at the interface between the tribo–layer and the subsurface; (c\u003csub\u003e4\u003c/sub\u003e) Polycrystalline diffraction ring of the labeled region in Figure. c\u003csub\u003e3\u003c/sub\u003e; (c\u003csub\u003e5\u003c/sub\u003e) Polycrystalline diffraction ring of the labeled region in Figure. c\u003csub\u003e3\u003c/sub\u003e; (c\u003csub\u003e6\u003c/sub\u003e) High–resolution TEM photographs, magnified images of localized regions, and FFT maps of nanoparticles in the subsurface; (d\u003csub\u003e1\u003c/sub\u003e) Microscopic morphology of the tribo–layer on the cBN particle surface at 1000 ℃; (d\u003csub\u003e2\u003c/sub\u003e) Magnified view of the tribo–layer on the cBN particle surface. The table illustrates the elemental composition of the tribo–layer; (d\u003csub\u003e3\u003c/sub\u003e) High–resolution TEM photograph and FFT map of the cBN particle subsurface; (d\u003csub\u003e4\u003c/sub\u003e) High–resolution TEM photograph and FFT map of the cBN particle subsurfaces. The insets show the atomic models of BN particles with FCC structure and HCP structure.\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/5a44e370cf49889af4060e18.png"},{"id":79339594,"identity":"71be2fd5-1113-4234-9c3a-0ce60f3516f9","added_by":"auto","created_at":"2025-03-27 08:25:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1093280,"visible":true,"origin":"","legend":"\u003cp\u003e(a\u003csub\u003e1\u003c/sub\u003e, a\u003csub\u003e2\u003c/sub\u003e, and a\u003csub\u003e3\u003c/sub\u003e) IPF map, KAM map, and recrystallization map of the tribo–layer and subsurface of NiAlTa metal at 25 ℃; (b\u003csub\u003e1\u003c/sub\u003e and b\u003csub\u003e2\u003c/sub\u003e) IPF map and KAM map of the tribo–layer and subsurface of cBN particles at 25 ℃. The insets show the Kikuchi band contrast map (BC map); (c\u003csub\u003e1\u003c/sub\u003e, c\u003csub\u003e2\u003c/sub\u003e, and c\u003csub\u003e3\u003c/sub\u003e) IPF map, KAM map, and recrystallization map of the tribo–layer and subsurface of NiAlTa metal at 1000 ℃. The inset illustrates the curves of grain size versus depth for the grains in the tribo–layer; (d\u003csub\u003e1\u003c/sub\u003e and d\u003csub\u003e2\u003c/sub\u003e) IPF map and KAM map of the tribo–layer and subsurface of cBN particles at 1000 ℃. The inset shows the BC map.\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/73531f7b5a3fea577fc08eab.png"},{"id":90345191,"identity":"630c5f32-4ad2-4426-a8d8-3981bde97d4d","added_by":"auto","created_at":"2025-09-01 16:10:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":10739474,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/5cb30be1-aed2-4f30-987e-a706106a28a2.pdf"},{"id":79339584,"identity":"45efc38b-69d2-4400-a13b-8091e398fd00","added_by":"auto","created_at":"2025-03-27 08:25:12","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":495607,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGRAPHICAL ABSTRACT\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-6275026/v1/d20ec2f14a3b5acc32a81e3d.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Tribo–Driven Evolution of Specific Nano–heterostructures to Achieve Exceptional Wear Resistance in Composites","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eMetal\u0026ndash;ceramic composites become one of the core materials in advanced manufacturing by breaking through the performance limits of traditional metal materials through the precise design of components and structures [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The designability of properties (e.g., wear resistance) and engineering applicability of metal\u0026ndash;ceramic composites are continuously expanded. A successful case is the use of MCrAlYX/cBN composites for turbine blade tips to achieve wear and impact resistance in aero\u0026ndash;engines [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Unfortunately, conventional MCrAlYX/cBN composites can no longer meet the operating environment requirements of hot\u0026ndash;end turbines (\u0026gt;\u0026thinsp;1000 ℃), and suffer from low high\u0026ndash;temperature strength, severe wear, and difficulty in retaining ceramic particles [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. A candidate NiAlTa/cBN composite is proposed. Due to the lack of in\u0026ndash;depth studies on this composite, its failure mechanism in dry sliding wear is still unclear. Therefore, it is necessary to understand the wear mechanism comprehensively to guide the further optimization of material properties.\u003c/p\u003e \u003cp\u003eThe wear mechanism of metal\u0026ndash;ceramic composites is influenced by the material composition (e.g., the ratio of metallic to ceramic phases) and microstructure (e.g., distribution and size of ceramic particles, interfacial bonding state). In high\u0026ndash;temperature dry sliding wear, the wear mechanism of metal\u0026ndash;ceramic composites shifts from being controlled by the delamination and oxidation of the metal to being related to the wear and fracture of the ceramic particles as the proportion of the ceramic phase increases [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The transition of the wear mechanism depends on the sensitivity of the internal structure or elements of the metal and ceramic to temperature and tribo\u0026ndash;chemical reactions. Nanoscale (\u0026lt;\u0026thinsp;100 nm) and microscale ceramic particles (\u0026gt;\u0026thinsp;10 \u0026micro;m) affect the wear mechanism of composites by influencing the microcomposition, the tribo\u0026ndash;oxidation behavior, and the evolution of the tribo\u0026ndash;layer of the metal. For example, Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e ceramic particles altered the phase composition of the CoCrAlYTa material produced by laser-induction hybrid cladding, which transformed severe adhesive wear into micro\u0026ndash;cutting mechanism with a low wear rate [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Adhesive wear characterized by a high wear rate and a high coefficient of friction caused by nanoparticles is undesirable [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Microceramic particles can significantly improve this disadvantage and impact resistance by modifying the interface contact state, but they may act as a source of cracks. In addition, the interfacial bonding state between metal and ceramic also exerts an important influence. Three\u0026ndash;body abrasive wear caused by ceramic particle detachment due to weak interfacial bonding increases wear rate and coefficient of friction fluctuations. By applying a metal layer or an interfacial reaction layer on the ceramic particle surface to realize the wetting between metal and ceramic (e.g., the wettability of Co on WC [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], the formation of Ni₃Ti from TiC and Ni [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]), the transfer of effective load and the delay of interfacial exfoliation can be achieved to improve the wear resistance of composites.\u003c/p\u003e \u003cp\u003eIn high\u0026ndash;temperature dry sliding wear, a transition in the wear mechanism of metal\u0026ndash;ceramic composites has been defined as a function of temperature. This transition is closely related to the evolution of the tribo\u0026ndash;layer on the metal and ceramic surfaces. The tribo\u0026ndash;layer induced by sliding wear controls the wear process as it is where the friction energy is dissipated and accommodates the stress, speed, and temperature gradients. Oxides serve as the basic units that make up the tribo\u0026ndash;layer. Generally, the tribo\u0026ndash;layer is formed by repeated fragmentation, compaction, and sintering of oxide wear debris, which can accommodate elastic\u0026ndash;plastic deformation and virtually eliminate wear [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. For example, the CoCrAlYTaCSi/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e composites underwent a transition from severe to mild wear as the temperature increased. After the formation of the tribo\u0026ndash;layer, the wear rate of the composites was reduced by an order of magnitude [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Temperature usually influences the evolution of the tribo\u0026ndash;layer and the wear mechanism by affecting the oxidation rate of the metal, the mode of mechanical deformation, and the sintering rate of the oxide wear debris. Currently, three mechanisms have been proposed to explain the evolution of the tribo\u0026ndash;layer and the transformation of the wear mechanism [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], namely, the \u0026ldquo;metal debris\u0026rdquo; mechanism, the \u0026ldquo;oxidation\u0026ndash;scratch\u0026ndash;re\u0026ndash;oxidation\u0026rdquo; mechanism, and the \u0026ldquo;complete oxidation\u0026rdquo; mechanism. However, the micromechanisms of chemical stability of ceramic particles in high\u0026ndash;temperature sliding wear are not well investigated. Limited studies showed that the competition between oxygen\u0026ndash;assisted surface decarburization and toughening of the nano\u0026ndash;oxide tribo\u0026ndash;layer of TiC particles in high\u0026ndash;temperature sliding wear determined the wear mechanism of Fe\u0026ndash;TiC composites [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Thus, it can be seen that the tribo\u0026ndash;layers on the metal and ceramic surfaces may not be isolated from each other, and they are connected and together influence the wear mechanism of metal\u0026ndash;ceramic composites.\u003c/p\u003e \u003cp\u003eBesides the tribo\u0026ndash;layers on the metal and ceramic surfaces, the microstructure evolution of the subsurfaces induced by sliding wear also affects the wear resistance of metal\u0026ndash;ceramic composites. In general, plastic deformation layers triggered by plastic deformation mediated by dislocations, stacking faults, or deformation twins, individually or jointly, become one of the responses of the microstructure of the subsurface. These responses also include high\u0026ndash;temperature\u0026ndash;induced dynamic recrystallization [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], dislocation\u0026ndash;mediated grain refinement [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and grain boundary migration\u0026ndash;controlled grain growth [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In high\u0026ndash;temperature sliding wear, the subsurface plastic deformation layer is not directly involved in the sliding process, and it only serves as a load\u0026ndash;bearing layer for the tribo\u0026ndash;layer. The stability of the plastic deformation layer affects the tribological behavior of the composite. Strain localization due to the continuous accumulation of plastic strain leads to crack nucleation at the metal\u0026ndash;ceramic interface. For example, cracks originating from Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e particles weakened the mechanical supporting effect on the tribo\u0026ndash;layer, resulting in a significant increase in the wear rate of CoNiCrAlY/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e composites [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. In addition, the microstructure of ceramic particles changes with load and temperature. For example, the movement and multiplication of dislocations induced by friction loading caused microplastic deformation of WC ceramic particles at high temperatures [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn high\u0026ndash;temperature sliding wear, an in\u0026ndash;depth study of the evolution of nano\u0026ndash;heterostructures controlling the tribological behavior is crucial for optimizing the wear resistance of composites. Therefore, spark\u0026ndash;plasma\u0026ndash;sintered NiAlTa/cBN composites are used as a model system to investigate the stress\u0026ndash; and temperature\u0026ndash;induced evolution of the tribo\u0026ndash;layers with specific nano\u0026ndash;heterostructures of the metal and ceramic surfaces and their effects on the tribological behavior. This work highlighted the significance of the tribo\u0026ndash;induced evolution of the tribo\u0026ndash;layers on the wear resistance of the composite. A strategy to achieve exceptional wear resistance by regulating the evolution of specific nano\u0026ndash;heterostructures on the composite surfaces was proposed.\u003c/p\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cp\u003e\u003cstrong\u003eMaterial Characterization.\u003c/strong\u003e Figure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ea shows the preparation process of NiAlTa/cBN composites, including powder mixing and spark plasma sintering (SPS). The principle of SPS is demonstrated in it. The mixed powder is placed in a graphite die. The powder particles undergo plastic deformation, rearrangement, and diffusion joining to achieve material densification under the synergistic effect of pulsed current, pressure, and rapidly elevated temperature. Figure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eb displays the microscopic morphology of NiAlTa/cBN mixed powders. The size statistic in the inset illustrates that the average particle size of the metal powder is about 40 \u0026micro;m. The microscopic morphology and EDS mapping of Ni\u0026ndash;coated cBN particles are showed in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ec. The Ni layer is prepared by chemical plating, which is well combined with cBN particles. High\u0026ndash;resolution TEM photograph and fast fourier transform map (FFT map) confirm that the BN particles are characterized by a typical face\u0026ndash;centered cubic (FCC) structure (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ed). The presence of defects such as lattice distortions and vacancies indicates that the cBN particles are non\u0026ndash;stoichiometric, which is caused by the filling of vacancies of nitrogen atoms by oxygen atoms (BN\u003csub\u003e1\u0026ndash;x\u003c/sub\u003e[\u003cem\u003eV\u003c/em\u003e\u003csub\u003eN\u003c/sub\u003e]) [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. The atomic model of the FCC structure of cBN is shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ed.\u003c/p\u003e\n\u003cp\u003eThe tribological behavior of the composites depends on their microstructure and phase composition. Figure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ee illustrates the backscattered electron morphology (BSE) of NiAlTa/cBN composites. A good infiltration between cBN particles and NiAlTa metal is achieved. The difference in the contrast indicates that besides the cBN particles, the gray matrix phase and white nanoparticles diffusely distributed in its interior or grain boundaries are found in the NiAlTa/cBN composites. TEM bright field image and EDS mapping of the gray phase and white nanoparticles are shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ef. White nanoparticles are enriched with the heavy metal element Ta. High\u0026ndash;resolution TEM photograph and fast fourier transform (FFT) map at their interfaces show that the gray phase and white nanoparticles are \u0026beta;\u0026ndash;NiAl with B2\u0026ndash;type ordered body\u0026ndash;centered cubic structure and (Ni, Al)Ta with C14\u0026ndash;type hexagonal structure, respectively (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eg). (Ni, Al)Ta phase is preferentially formed at the grain boundaries of the \u0026beta;\u0026ndash;NiAl phase. (Ni, Al)Ta phase is a topological close\u0026ndash;packed phase (TCP) with a MgZn\u003csub\u003e2\u003c/sub\u003e\u0026ndash;type laves lattice. Compared with the body\u0026ndash;centered cubic structure, this crystal structure has higher lattice friction giving it high hardness and high\u0026ndash;temperature stability [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e]. In addition, an incoherent interface of cubic to hexagonal structure between the \u0026beta;\u0026ndash;NiAl phase and the (Ni, Al)Ta phase is observed. The poor lattice match and weak interfacial bonding strength are highly susceptible to becoming a source of cracks and reduce the toughness of the composites [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e]. XRD result reconfirms the presence of these phases (Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eh).\u003c/p\u003e\n\u003cp\u003eThe dispersion of ceramic particles directly affects the tribological behavior of the composites. The distribution of cBN particles was analyzed by a microscopic computed tomography (CT) technique. The results are displayed in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ei. The CT results show that the cBN particles are uniformly dispersed in NiAlTa metal. The good dispersion of cBN particles is favorable for the wear resistance of the composites. Nano\u0026ndash;hardness and elastic modulus are fundamental quantitative parameters to measure the mechanical properties of materials at the micro\u0026ndash; and nanoscale. The load\u0026ndash;displacement curves of the nanoindentation experiments of NiAlTa metal are shown in Fig. \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003ej. The inset illustrates the micro\u0026ndash;Vickers hardness of the NiAlTa metal and cBN particle. Parameters derived from the nanoindentation experiments related to the wear characteristics of the material are listed in the table. The nanoindentation data for cBN ceramic particles are obtained from the literature [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e]. The micro\u0026ndash;Vickers hardness and nanoindentation data show that cBN particles have much higher (nano)hardness and elastic modulus than NiAlTa metals. Notably, the addition of Ta atoms substantially increases the hardness of the \u0026beta;\u0026ndash;NiAl phase. This is related to the dispersion\u0026ndash;strengthening effect of the nanoparticles and the solid\u0026ndash;solution strengthening effect of the Ta atoms. According to the classical Archard\u0026apos;s law [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e], the increase in hardness improves the wear resistance of the material. The high hardness and elastic modulus confer high resistance to mechanical degradation and failure of cBN particles.\u003c/p\u003e\n\u003cp\u003eThe \u003cem\u003eH\u003c/em\u003e/\u003cem\u003eE\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e ratio indicates the penetration depth that a material can withstand without exceeding its elastic limit. A high \u003cem\u003eH\u003c/em\u003e/\u003cem\u003eE\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e ratio is desirable because it implies that the material has a long \u0026ldquo;elastic strain failure\u0026rdquo; time to allow the applied load to be redistributed over a large area without strain localization. Also, a high \u003cem\u003eH\u003c/em\u003e/\u003cem\u003eE\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e ratio indicates that there are few roughness peaks on the wear surface where the force exceeds its elastic limit, which may lead to a reduction in the coefficient of friction [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e]. The high \u003cem\u003eH\u003c/em\u003e/\u003cem\u003eE\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e ratio implies that cBN particles have excellent wear resistance and a low coefficient of friction. Another parameter related to wear characteristics is \u003cem\u003eH\u003c/em\u003e\u003csup\u003e3\u003c/sup\u003e/\u003cem\u003eE\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e, which indicates the ability of a material to resist plastic deformation in loaded contact, namely the yield strength [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e]. A ratio two orders of magnitude larger indicates that cBN particles have a better ability to resist plastic deformation. In addition, the elastic recovery rate \u003cem\u003e\u0026eta;\u003c/em\u003e is also related to the wear characteristics of metallic materials. \u003cem\u003e\u0026eta;\u003c/em\u003e is defined as the ratio of the elastic deformation energy (\u003cem\u003eE\u003c/em\u003e\u003csub\u003eelastic\u003c/sub\u003e) to the total deformation energy (\u003cem\u003eE\u003c/em\u003e\u003csub\u003etotal\u003c/sub\u003e) during the loading\u0026ndash;unloading process [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]. The elastic recovery rate reflects the cracking resistance of the material. The total deformation energy during loading is represented by the area under the loading curve (\u003cem\u003eL\u003c/em\u003e) from the surface to the maximum depth of indentation (\u003cem\u003eh\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e) (\u003cem\u003eS\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eS\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e). The elastic deformation energy during unloading is represented by the area under the unloading curve (\u003cem\u003eL\u003c/em\u003e\u0026prime;) between the final indentation depth (\u003cem\u003eh\u003c/em\u003e\u003csub\u003ef\u003c/sub\u003e) and the maximum indentation depth (\u003cem\u003eh\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e) (\u003cem\u003eS\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003eThe high elastic recovery rate suggests that cBN particles have better crack resistance than NiAlTa metals. This is unexpected.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFriction and Wear Studies.\u003c/strong\u003e The friction and wear experimental principle is demonstrated in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea. Under a specific load, speed, and displacement, the upper specimen ball remains relatively stationary and the lower specimen plate reciprocates to achieve sliding wear. The real\u0026ndash;time coefficient of friction (COF) curves of NiAlTa/cBN composites sliding against ZrO\u003csub\u003e2\u003c/sub\u003e ceramic balls at different temperatures and loads are shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb and Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec, respectively. With the increase of normal loads or temperatures, the COFs of NiAlTa/cBN composites show a decreasing or increasing trend. However, the COFs do not show a strict negative or positive correlation with loads or temperatures. The variation in the COFs indicates that the NiAlTa/cBN composites undergo different wear mechanisms under different experimental conditions. This may be related to the evolution of the microstructure and chemical composition of the tribo\u0026ndash;layers and subsurfaces or the real contact state between the friction pairs. It is noteworthy that compared with the pure NiAlTa metallic material, the COF is reduced by half when micron\u0026ndash;sized cBN particles are added [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. This may be attributed to the \u0026ldquo;friction reduction\u0026rdquo; effect of cBN particles and local chemical composition fluctuations. In particular, compared with the conventional phenomenon, an abnormal increase in COF with increasing temperature is observed in this system. This result is related to the complex interaction of temperature and load that affects the evolution of the wear products or tribo\u0026ndash;layers. The real\u0026ndash;time COF curve is an important reflection of the \u0026ldquo;formation\u0026ndash;breakdown\u0026ndash;reorganization\u0026rdquo; process of the tribo\u0026ndash;layer. From Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb and Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec, it can be found that the real\u0026ndash;time COF curves are divided into two stages, namely, the running\u0026ndash;in stage (fragmentation and compaction of wear debris) and the stabilization stage (rupture\u0026ndash;reorganization stage). Changes in thermal\u0026ndash;contact stresses in localized areas may lead to the breakdown of the tribo\u0026ndash;layer. Cracks or spalling pits may develop within the tribo\u0026ndash;layer due to fretting wear under cyclic stresses [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. Fluctuating real\u0026ndash;time COFs reflect this.\u003c/p\u003e\n\u003cp\u003eThe average wear rates of NiAlTa/cBN composites at different temperatures and loads are displayed in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed. The average wear rate of NiAlTa/cBN composites is negatively correlated with load and positively correlated with temperature. At 25 ℃, the average wear rate of NiAlTa/cBN composites reaches a minimum value (4.25 \u0026times; 10\u003csup\u003e\u0026ndash;7\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e\u0026middot;N\u003csup\u003e\u0026ndash;1\u003c/sup\u003e\u0026middot;m\u003csup\u003e\u0026ndash;1\u003c/sup\u003e). The large slope indicates a high\u0026ndash;temperature sensitivity of the wear rate of NiAlTa/cBN composites. This may be related to the tribo\u0026ndash;induced microstructure and chemical composition of the tribo\u0026ndash;layers and subsurfaces of the cBN particles and NiAlTa metal. Figure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ee shows a plot of the average wear rate of NiAlTa/cBN composites of SPS compared with the conventional composites obtained with different processes or techniques. Compared with the conventional composites, the NiAlTa/cBN composites have lower wear rates over a wide temperature range, which indicates that the NiAlTa/cBN composites exhibit excellent wear resistance. The ultra\u0026ndash;low wear rate at room temperature is observed. This is one of the lowest wear rates reported so far. The excellent wide temperature range wear resistance is attributed to the composition and structural design of the composite. On the one hand, it is attributed to the composition of the composites. The soft\u0026ndash;hard combination of \u0026beta;\u0026ndash;NiAl\u0026ndash;(Ni, Al)Ta has good resistance to high\u0026ndash;temperature softening and strain hardening induced by heterogeneous deformation [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e], preventing the occurrence of failure behaviors such as cBN particles being pulled out. The soft\u0026ndash;hard combination of \u0026beta;\u0026ndash;NiAl\u0026ndash;(Ni, Al)Ta can effectively coordinate the local deformation and distribute the elastic\u0026ndash;plastic strain at high temperatures to inhibit the crack initiation and extension. On the other hand, it is attributed to the structural design of the composites. The micrometer cBN particles with high hardness and high elastic modulus provide good load support and stress transfer, which retard the increase of the true contact area. Meanwhile, NiAlTa metal with multiple deformation pathways disperses the stresses in cBN particles and allows NiAlTa/cBN composites to undergo synergistic deformation without damage. These are proven in the subsequent sections.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eWear Mechanism.\u003c/strong\u003e To elucidate the effect of load and temperature on the wear mechanism of NiAlTa/cBN composites, typical macroscopic wear morphology is presented in Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. Figure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ea shows the macroscopic wear morphology of NiAlTa/cBN composites at 25 ℃ and 100 N. The lower left inset illustrates the wear morphology of a paired ZrO\u003csub\u003e2\u003c/sub\u003e ceramic ball. At low temperatures and high loads, the NiAlTa metal experiences only a mild plastic deformation. The pulling out of cBN particles is not observed. The shear stress \u003cem\u003e\u0026delta;\u003c/em\u003e\u003csub\u003exz\u003c/sub\u003e calculated based on the Hamilton model is a powerful tool to evaluate the elastic or plastic behavior of composites under friction loading [\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]. The calculated shear stress (\u003cem\u003e\u0026delta;\u003c/em\u003e\u003csub\u003exz\u003c/sub\u003e) field in the subsurface of NiAlTa metal and cBN particles based on the Hamilton model is displayed in Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eb. The calculated shear stress shows a gradient distribution along the depth below the sliding surface. At the beginning of the sliding contact, the shear stress values in the NiAlTa metal (635 MPa) are slightly higher than those in the cBN particles (610 MPa). However, all these shear stress values are much smaller than the yield strength of NiAlTa metal (~\u0026thinsp;1200 MPa) [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e] and the compressive strength of cBN particles (~\u0026thinsp;38000 MPa) [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e]. Both NiAlTa metal and cBN particles are within the elastic deformation range under friction loading. The ultra\u0026ndash;low wear rate suggests that NiAlTa/cBN composites may be nearly wear\u0026ndash;free at low temperatures and high loads through the anti\u0026ndash;friction and anti\u0026ndash;wear effect of the tribo\u0026ndash;layer or the structural stability that resists strain localization. In addition, dislocation motion within the metal and ceramic may not be easily triggered during sliding wear. However, strain localization or cracking can still occur in the topmost layer of the material due to the introduction of a large number of defects, leading to damage or roughening of the surface [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. This is hard to avoid.\u003c/p\u003e\n\u003cp\u003eUnder the indentation of paired microconvexes, grooves are found as a typical feature of abrasive wear on the wear surfaces of NiAlTa metals, cBN particles, and ZrO\u003csub\u003e2\u003c/sub\u003e ceramic balls. Grooves are caused by two\u0026ndash; or three\u0026ndash;body abrasive wear resulting from wear particles generated and retained between the two surfaces during repeated sliding process. In addition, the large hardness difference between NiAlTa metal and cBN ceramic particles causes NiAlTa metal to be preferentially worn in dry sliding wear. This is confirmed by the height difference at the metal/ceramic particle interface illustrated in the upper right inset. The protruding cBN particles bear the majority of the stress in the subsequent sliding wear. This may be one of the reasons why NiAlTa/cBN composites have the lowest wear rate at room temperature.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ec and Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ed show the macroscopic wear morphology of NiAlTa/cBN composites at 1000 ℃ for 10 N and 100 N, respectively. The lower left inset exhibits the wear morphology of the paired ZrO\u003csub\u003e2\u003c/sub\u003e ceramic ball. The reduction of the strength of the ZrO\u003csub\u003e2\u003c/sub\u003e ceramic balls due to the high temperature leads to severe wear at both low and high loads (corresponding to large diameters). The increase in the contact area between the friction pairs reduces the wear rate by decreasing the contact stress. The ZrO\u003csub\u003e2\u003c/sub\u003e wear debris generated by the wear can be captured in the wear scars and is strongly involved in the subsequent sliding process. The number of grooves parallel to the sliding direction is significantly reduced, indicating that sliding\u0026ndash;induced abrasive wear is avoided. In addition, white\u0026ndash;green paste\u0026ndash;like substances are found on the worn surfaces. The higher normal load results in a more homogeneous distribution of the paste\u0026ndash;like substance. The Raman spectra of the upper right inset in Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003ee show that the white\u0026ndash;green paste\u0026ndash;like substance is a mixture of ZrO\u003csub\u003e2\u003c/sub\u003e and Ta\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e. This could be the reason why the coefficient of friction is halved when micron\u0026ndash;sized cBN particles are added. In addition, the bright tribo\u0026ndash;layer is found, which is attributed to the friction heat and the poor thermal conductivity of the oxidized particle layer.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ea, Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eb, and Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec show the microscopic wear morphology of NiAlTa/cBN composites at 25 ℃ and 100 N, 1000 ℃ and 10 N, and 1000 ℃ and 100 N, respectively. Besides the features observed in the macroscopic morphology, tribo\u0026ndash;induced tribo\u0026ndash;layers and cracking or spalling of the cBN particles under high loads or high temperatures are found. The presence of cracks in the tribo\u0026ndash;layer tends to make the tribo\u0026ndash;layer delaminated. At high temperatures, fine wear debris is observed, which is a typical feature of oxidative wear [\u003cspan class=\"CitationRef\"\u003e8\u003c/span\u003e]. The generation of fine wear debris is a prerequisite for the formation of the tribo\u0026ndash;layer. EDS analysis reveals that the tribo\u0026ndash;layer on the NiAlTa metal surface is enriched with elements such as B, O, and Zr. The worn cBN particle surface is enriched with the element O (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ed). This indicates that tribo\u0026ndash;or high\u0026ndash;temperature\u0026ndash;induced chemical mixing or reaction is significantly triggered on the NiAlTa metal and cBN particle surfaces. The cracking or spalling of cBN particles is closely related to the changes in their fracture toughness. The inset of Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ec shows the indentation fracture toughness (\u003cem\u003eK\u003c/em\u003e\u003csub\u003eIC\u003c/sub\u003e) and microhardness of cBN particles before and after wear. The fracture toughness (\u003cem\u003eK\u003c/em\u003e\u003csub\u003eIC\u003c/sub\u003e) was calculated by using Shetty\u0026apos;s equation [\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\n\u003cp\u003eWhere \u003cem\u003eK\u003c/em\u003e\u003csub\u003eIC\u003c/sub\u003e is the indentation fracture toughness; \u003cem\u003eP\u003c/em\u003e is the indentation load; \u003cem\u003ea\u003c/em\u003e is half of the indentation size; and \u003cem\u003el\u003c/em\u003e is the crack length measured from the indentation corner. The fracture toughness measurement obtained in this way does not represent the true fracture toughness of cBN. However, the measurements can qualitatively characterize the effect of chemical changes on the cBN particle surface on its hardness and fracture toughness before and after sliding wear [\u003cspan class=\"CitationRef\"\u003e1\u003c/span\u003e]. Compared with the cBN particles before the experiment (8.51 MPa\u0026middot;m\u003csup\u003e1/2\u003c/sup\u003e and 6082 HV), the cBN particles after sliding wear exhibit high hardness and low \u003cem\u003eK\u003c/em\u003e\u003csub\u003eIC\u003c/sub\u003e (4.49 MPa\u0026middot;m\u003csup\u003e1/2\u003c/sup\u003e and 8088 HV). This indicates that the cBN particles become hard and brittle after high\u0026ndash;temperature sliding wear due to changes in surface chemical composition. Therefore, it is reasonable to assume that the formation of oxides on the particle surface increases the tendency of crack nucleation and destroys the integrity of the ceramic particles during sliding. This is in contrast to the toughening effect of TiC particles due to surface chemical changes.\u003c/p\u003e\n\u003cp\u003eRaman spectra of the cBN particle surface show that besides the scattering peaks of non\u0026ndash;stoichiometric cBN\u003csub\u003e1\u0026ndash;x\u003c/sub\u003e and B, high\u0026ndash;temperature\u0026ndash;induced B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e is detected (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ee). Figure \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ei demonstrates the oxidation process of cBN\u003csub\u003e1\u0026ndash;x\u003c/sub\u003e particles at high temperatures. The high concentration of vacancies present in the non\u0026ndash;stoichiometric cBN\u003csub\u003e1\u0026ndash;x\u003c/sub\u003e particles is occupied by O or N atoms from the air. After the desorption of O or N atoms occurs, the cBN\u003csub\u003e1\u0026ndash;x\u003c/sub\u003e particles react with O\u003csub\u003e2\u003c/sub\u003e to produce B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e and release N\u003csub\u003e2\u003c/sub\u003e [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. During the oxidation process, cBN\u003csub\u003e1\u0026ndash;x\u003c/sub\u003e particles may crack due to internal stress release or cleaving effect [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. This may also be the cause of the cracking of cBN particles. B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e can exist in a crystal or amorphous state. The atomic model of crystalline B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e is shown in the inset. The low melting point of B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (~\u0026thinsp;450 ℃) in a liquid state at 1000 ℃ reduces the coefficient of friction and wear rate.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003ef shows the Raman spectra of the tribo\u0026ndash;layer on the NiAlTa metal surface. Raman spectra suggest that the tribo\u0026ndash;layer consists of ZrO\u003csub\u003e2\u003c/sub\u003e, Ta\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e, Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, and NiO oxides. In room\u0026ndash;temperature sliding wear, the tribo\u0026ndash;oxidation process is promoted by deformation heat, friction heat, and increasing particle energy [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e]. When the wear debris particles are extremely fine, the fine metal particles may be completely oxidized spontaneously under certain conditions [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e]. Thus, oxides are produced even at room temperature. The weak and broad peaks of the oxides are observed, which indicates a low amount of oxides and a high degree of amorphization in the tribo\u0026ndash;layer. In high\u0026ndash;temperature sliding wear, the Raman spectra with high number and strong scattering peaks imply that ZrO\u003csub\u003e2\u003c/sub\u003e and Ta\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e are the main constituents of the tribo\u0026ndash;layer. In addition, it is noteworthy that the scattering peaks of Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e are detected at 1000 ℃, which suggests that the Ta element may have a tribo\u0026ndash;chemical reaction with the cBN particles. Figure \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eg illustrates the ionic potential and melting point of the oxides in the friction pair. Hard or lubricant oxides classified according to crystal\u0026ndash;chemical theory also play an important influence on the transformation of the wear mechanism in high\u0026ndash;temperature sliding wear. According to the crystal\u0026ndash;chemical theory, oxides with high ionic potential (\u003cem\u003e\u0026phi;\u003c/em\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eZ\u003c/em\u003e/\u003cem\u003er\u003c/em\u003e, \u003cem\u003eZ\u003c/em\u003e is the cation charge and \u003cem\u003er\u003c/em\u003e is the cation radius)) have excellent lubricating and anti\u0026ndash;wear properties [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. Therefore, B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (\u003cem\u003e\u0026phi;\u003c/em\u003e\u0026thinsp;=\u0026thinsp;12) and Ta\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e (\u003cem\u003e\u0026phi;\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.8) as lubricant oxides may reduce the coefficient of friction and wear rate of the composites.\u003c/p\u003e\n\u003cp\u003eIn high\u0026ndash;temperature sliding wear, the tribo\u0026ndash;layer is formed by repeated fragmentation, compaction, and sintering of oxide wear debris [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e]. The wear debris, as the basic unit that makes up the tribo\u0026ndash;layer, reduces the COF or wear rate by eliminating the contact between the friction pairs, increasing the surface hardness, or generating lubrication products. Our previous studies showed that when ZrO\u003csub\u003e2\u003c/sub\u003e ceramic balls are used as high\u0026ndash;temperature sliding pair, wear\u0026ndash;induced ZrO\u003csub\u003e2\u003c/sub\u003e wear debris usually serves as the main constituent of the tribo\u0026ndash;layer (\u0026gt;\u0026thinsp;70%). This is consistent with the results observed in this study. When this tribo\u0026ndash;layer slid against the paired ZrO\u003csub\u003e2\u003c/sub\u003e ceramic balls, a high COF was caused due to the high similarity (e.g., similar physical/chemical properties, lattice parameters) between the friction pairs [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. Here, when high normal loads are applied (more and large sized ZrO\u003csub\u003e2\u003c/sub\u003e wear debris is generated), ZrO\u003csub\u003e2\u003c/sub\u003e wear debris exceeding the critical wear debris size is removed from the wear scar without participating in the formation of the tribo\u0026ndash;layer at a constant temperature. At this point, according to the crystal\u0026ndash;chemical theory, the high\u0026ndash;temperature\u0026ndash;induced generation of oxides with high ionic potentials (e.g., Ta\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e, B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) of the metal or cBN particles is the main reason for the reduction in the COF and wear rate.\u003c/p\u003e\n\u003cp\u003eTemperature usually affects the evolution of the tribo\u0026ndash;layer by influencing the oxidation rate, the mechanical deformation mode, and the wear debris sintering rate. The formation of the tribo\u0026ndash;layer depends on the sensitivity to tribo\u0026ndash;chemical reactions of the internal structure or elements of the alloy matrix [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]. Here, when high temperatures are applied, the formation of an Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e protective film from the selective oxidation of Al greatly slows down the oxidation rate of NiAlTa metals. That is, the oxidation products of the metal are not sufficient to control the formation of the tribo\u0026ndash;layer. However, the increasing adhesion force between the wear debris due to high temperature leads to the participation of large size and quantity of ZrO\u003csub\u003e2\u003c/sub\u003e wear debris in the subsequent sliding wear and dominates the formation of the tribo\u0026ndash;layer [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e]. As a result, a high COF is caused. In addition, high melting point oxides such as ZrO\u003csub\u003e2\u003c/sub\u003e (2680 ℃), NiO (1987 ℃), and Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e (2040 ℃) endow the tribo\u0026ndash;layer with high hardness, leading to a low wear rate. The formation rate and coverage of the tribo\u0026ndash;layer increase with increasing temperature. The direct contact between the friction pairs is reduced and the wear rate is lowered.\u003c/p\u003e\n\u003cp\u003eAt atmospheric pressure, the cBN \u0026rarr; hBN phase transition usually occurs in the temperature range\u0026thinsp;\u0026gt;\u0026thinsp;1500 ℃ [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. Interestingly, the tribo\u0026ndash;induced cBN \u0026rarr; hBN phase transition is observed in sliding wear experiments at 1000 ℃. The possible reasons for this are as follows: Firstly, in high\u0026ndash;temperature sliding wear, after some of the exfoliated cBN particles are repeatedly fragmented to submicron size, the phase transition temperature is significantly lowered, which makes the cBN \u0026rarr; hBN phase transition possible at 1000 ℃. Secondly, under cyclic stress, high\u0026ndash;temperature or tribo\u0026ndash;induced mechanical mixing of B\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e with cBN particles promotes the cBN \u0026rarr; hBN phase transition [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. The sublimation pits on the cBN particle surface and the Raman scattering peaks of hBN demonstrated in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eh both confirm the occurrence of the phase transition. In this experiment, the cBN \u0026rarr; hBN phase transition may proceed through the solid\u0026ndash;state transformation mechanism (cBN \u0026rarr; rBN \u0026rarr; hBN) and the CVD mechanism (sublimation and formation of single\u0026ndash;atom SP\u003csup\u003e2\u003c/sup\u003e bonds on the cBN particle surface) [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. The phase transition mechanism is summarized in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eh. The sublimation pits observed on the cBN particle surface confirm the existence of the CVD mechanism. Evidence for the solid\u0026ndash;state transformation mechanism is provided in the next section. The generation of phase\u0026ndash;transition induced hBN contributes to the reduction of the COF and wear rate of NiAlTa/cBN composites.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEvolution of Tribo\u0026ndash;induced Tribo\u0026ndash;layers and Plastic Deformation Layers With Nano\u0026ndash;heterostructures.\u003c/strong\u003e The tribo\u0026ndash;layer with nano\u0026ndash;heterostructures induced by sliding wear controls the friction and wear process as it is where the friction energy is dissipated and accommodates stress, speed, and temperature gradients. High\u0026ndash;resolution FIB/TEM was used to characterize the fine microstructure and chemical composition of the tribo\u0026ndash;layer formed in the room and high\u0026ndash;temperature sliding wear. The results are shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e. The tribo\u0026ndash;layers on the NiAlTa metal and cBN particle surfaces were observed separately.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea and Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eb show the tribo\u0026ndash;layers on the NiAlTa metal and cBN particle surfaces at room temperature, respectively. The microscopic morphology of the tribo\u0026ndash;layer on the NiAlTa metal surface is illustrated in \u003cstrong\u003eFig.\u0026nbsp;5a\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e. The tribo\u0026ndash;layer with a thickness of about 25 nm is found. EDS analysis shows that the tribo\u0026ndash;layer consists of O, Al, Ni, Zr, and Ta elements. A high density of dislocations is observed in the subsurface, accompanied by the appearance of dislocation tangles. High\u0026ndash;resolution TEM photograph, fast fourier transform map (FFT map), and inverse fast fourier transform map (IFFT map) of the tribo\u0026ndash;layer are shown in \u003cstrong\u003eFig.\u0026nbsp;5a\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e. The tribo\u0026ndash;layer is characterized by a disordered amorphous state. This is confirmed by the diffraction halo in the FFT map. The IFFT map indicates the presence of a large number of dislocations in the \u0026beta;\u0026ndash;NiAl phase. It is noteworthy that the \u0026beta;\u0026ndash;NiAl phase does not undergo dislocation\u0026ndash;mediated grain refinement, which serves as one of the typical sub\u0026ndash;surface microstructural responses in sliding wear. This implies that the tribo\u0026ndash;layer accommodates the plastic deformation induced by sliding wear. Furthermore, the lattice strain (\u003cem\u003e\u0026epsilon;\u003c/em\u003e\u003csub\u003exy\u003c/sub\u003e) map of \u003cstrong\u003eFig.\u0026nbsp;5a\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e obtained by geometrical phase analysis (GPA) suggests the presence of severe lattice distortion within the tribo\u0026ndash;layer (Fig. 5\u003cstrong\u003ea\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e). Therefore, it is reasonable to infer that the amorphization of the tribo\u0026ndash;layer on the NiAlTa metal surface is attributed to the plastic deformation\u0026ndash;induced solid\u0026ndash;state amorphization process. Reciprocating sliding leads to an increase in the number of dislocation boundaries and the free energy of the system [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. The high density of dislocations and other defects are concentrated in nano\u0026ndash;sized wear debris (e.g., ZrO\u003csub\u003e2\u003c/sub\u003e, Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e). When the free energy reaches a critical value, the lattice of the nanograins at the critical size collapses to release the elastic strain energy due to the lack of interatomic coordination. Structural disorder is introduced at the nanograin boundaries [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. In the subsequent sliding process, the amorphization gradually extends to the entire tribo\u0026ndash;layer. The doping of small\u0026ndash;sized O atoms accelerates the formation of amorphous products by altering the atomic coordination through directional bond contributions and large negative mixing enthalpies [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e]. Oxygen further weakens the lattice rigidity and makes the amorphous region easy to extend [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFigure 5b\u003c/strong\u003e \u003csub\u003e\u0026nbsp;\u003cstrong\u003e1\u003c/strong\u003e\u0026nbsp;\u003c/sub\u003e demonstrates the microscopic morphology and EDS mapping of the tribo\u0026ndash;layer on the cBN particle surface. Cracks perpendicular to the sliding direction are found. Amorphous substances with a similar chemical composition to the tribo\u0026ndash;layer in \u003cstrong\u003eFig.\u0026nbsp;5a\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e fill the cracks. This reconfirms that the amorphous tribo\u0026ndash;layer on the NiAlTa metal surface accommodates plastic strains well. A magnification of the tribo\u0026ndash;layer on the cBN particle surface is shown in \u003cstrong\u003eFig.\u0026nbsp;5b\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e. The tribo\u0026ndash;layer with a thickness of about 30 nm is found. EDS analysis suggests that the tribo\u0026ndash;layer is composed of the elements O, N, and Ta. Elliptical nanoparticles are distributed on the tribo\u0026ndash;layer surface. High\u0026ndash;resolution TEM photograph and FFT map indicate that the elliptical particles are Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e. The high\u0026ndash;hardness Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e particles can play the roles of load support and dispersion of contact stress. High\u0026ndash;resolution TEM photograph and FFT map of the tribo\u0026ndash;layer indicate that the tribo\u0026ndash;layer on the cBN particle surface also exhibits amorphous characteristics (Fig. 5\u003cstrong\u003eb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e). Raman spectra in the inset confirm the presence of Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e and Ta\u0026ndash;O\u0026ndash;N amorphous. The GPA map shows that a large number of defects (e.g., dislocations and vacancies) are found within the tribo\u0026ndash;layer and subsurface of the cBN particles (Fig. 5\u003cstrong\u003eb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e). In addition, in the cracks, localized atomic disorder regions are observed to appear along the nanograin boundaries (Fig.\u0026nbsp;5\u003cstrong\u003eb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/sub\u003e). This is a transitional stage of amorphization. The discovery of this evidence directly confirms the existence of the solid\u0026ndash;state amorphization process. In addition, the presence of Ta\u003csub\u003e2\u003c/sub\u003eB and Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e nanoparticles suggests that a chemical reaction between Ta and cBN occurs. Figure 5\u003cstrong\u003eb\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e6\u003c/strong\u003e\u003c/sub\u003e shows the atomic schematic of TaN and TaB\u003csub\u003e2\u003c/sub\u003e produced by the chemical reaction of Ta with cBN. TaN is formed through a diffusion reaction between Ta and cBN. This phenomenon is commonly found in high\u0026ndash;energy ball milling or mechanical grinding [\u003cspan class=\"CitationRef\"\u003e38\u003c/span\u003e]. The amorphization of the tribo\u0026ndash;layer on the cBN particle surface is attributed to the significant lattice distortion triggered by the doping of O atoms into the face\u0026ndash;centered cubic structure of the TaN lattice. This is similar to the amorphization process of Ta\u0026ndash;O\u0026ndash;N in reactive sputtering [\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e]. The above results indicate that the amorphous tribo\u0026ndash;layer on the NiAlTa metal and cBN particle surfaces at room temperature seems to be the main reason for the low COF and wear rate of NiAlTa/cBN composites.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ec and Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ed show the tribo\u0026ndash;layer on the NiAlTa metal and cBN particle surfaces at high temperatures, respectively. The microscopic morphology and EDS mapping of the tribo\u0026ndash;layer on the NiAlTa metal surface are demonstrated in \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e. The tribo\u0026ndash;layer consisting of nanoparticles is found. EDS analysis shows that the tribo\u0026ndash;layer is enriched with Zr elements. According to the Hall\u0026ndash;Petch relationship, the tribo\u0026ndash;layer composed of nanoparticles exhibits high hardness [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e]. This is favorable for wear resistance. The subsurface is enriched with element O, which suggests that the elements in the subsurface may be oxidized. A large number of holes and cracks are found within the tribo\u0026ndash;layer and subsurface. The large number of grain boundaries and defects such as holes or cracks within the tribo\u0026ndash;layer act as O internal diffusion channels. Also, nonequilibrium structures (e.g., vacancies, dislocations, and lattice distortions) in the tribo\u0026ndash;layer provide a pathway for the internal diffusion of oxygen atoms [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e]. Tribo\u0026ndash;induced high vacancy concentration tends to trigger the generation of micro-voids in the oxide layer, which makes the oxide layer loose and poorly protected. The presence of holes and cracks significantly weakens the bonding strength of the tribo\u0026ndash;layer. It is also noteworthy that the cracks are almost perpendicular to the wear surface. A magnified view of the tribo\u0026ndash;layer surfaces is shown in \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e. Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e nanoparticles are uniformly distributed on the tribo\u0026ndash;layer surface. The Raman spectra shown in the inset confirm the presence of Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e particles. Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e particles are not observed on the tribo\u0026ndash;layer surface of the NiAlTa metal surface at room temperature.\u003c/p\u003e\n\u003cp\u003eA localized magnified view of \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e is shown in \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e. A large number of holes and cracks extending along grain boundaries are found. Notably, the grains in the subsurface are significantly refined. In addition, numerous distortions and mismatched dislocations are present on the grain boundaries in the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer, which act as dislocation pinning points to hinder dislocation climbing and slipping and strengthen the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]. The \u0026beta;\u0026ndash;NiAl\u0026ndash;(Ni, Al)Ta structure undergoes degradation at high temperatures and high strains. This is caused by large contact loads at high temperatures. The polycrystalline diffraction rings of the labeled region in \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e are shown in \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e and \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e5\u003c/strong\u003e\u003c/sub\u003e. The polycrystalline diffraction ring shows that the tribo\u0026ndash;layer consists of ZrO\u003csub\u003e2\u003c/sub\u003e. The subsurface is composed of NiO, Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, and Ta\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e. These grains do not display significant texturing, as evidenced by the relatively uniform intensity of the diffraction ring. Figure\u0026nbsp;5\u003cstrong\u003ec\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e6\u003c/strong\u003e\u003c/sub\u003e demonstrates high\u0026ndash;resolution TEM photographs, local magnification, and FFT maps of the nanoparticles in the subsurfaces. All these results indicate that plenty of stacking faults and deformation twins exist within the subsurface. When the grain size decreases to tens of nanometers, the deformation is no longer controlled by normal slip but by partial dislocation activity, which predisposes to the formation of twins and stacking faults (SFs) [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e]. SFs can evolve into a source of stimulated dislocation multiplication. Meanwhile, deformed twins (DTs) hinder dislocation motion. Progressive and stable strengthening of subsurfaces is achieved [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]. Therefore, the high density of SFs and DTs\u0026ndash;mediated stabilized plastic deformation may be the reason for the excellent high\u0026ndash;temperature wear resistance and load\u0026ndash;bearing capacity of NiAlTa/cBN composites compared with other composites.\u003c/p\u003e\n\u003cp\u003eIn dry sliding wear, the huge hardness difference between metal and ceramic particles causes the metal to be worn preferentially. The cBN particles act as the main load\u0026ndash;bearing region. Concave areas such as NiAlTa metal areas serve as non\u0026ndash;load bearing areas, which act as \u0026ldquo;collectors\u0026rdquo; for wear debris such as ZrO\u003csub\u003e2\u003c/sub\u003e. The \u0026ldquo;collector\u0026rdquo; is also transformed into a load\u0026ndash;bearing region under stress and temperature, namely the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer. After the formation of the hard ZrO\u003csub\u003e2\u003c/sub\u003e surface layer, the contact between the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer and the ZrO\u003csub\u003e2\u003c/sub\u003e ceramic ball is mainly elastic. The wear rate of NiAlTa/cBN composites should supposedly be reduced, but this is not the case. Here, the subsurface controls the wear behavior of NiAlTa/cBN composites. The subsurface fine\u0026ndash;crystalline layer is triggered by plastic deformation mediated by a combination of dislocations, faults, or deformation twins. The subsurface fine\u0026ndash;crystalline layer does not directly participate in the sliding process, but only serves as a load\u0026ndash;bearing layer for the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer. Considering the high strength of the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer, the plastic deformation does not always start from the surface layer. Due to the gradient distribution of applied stress under the Hertzian contact, plastic deformation or strain localization within the subsurface layer occurs when the local stress exceeds the elastic limit of the subsurface material [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e]. The continuous accumulation of plastic strain makes the fine\u0026ndash;crystalline layer unstable and prone to cracks or holes at the metal/ceramic interface or grain boundaries at a certain depth below the contact surface. As observed in \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e and \u003cstrong\u003eFig.\u0026nbsp;5c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e. The oxidation of the elements aggravates the subsurface instability. The delamination wear due to strain localization is likely to be the main reason for the increased wear rate of NiAlTa/cBN composites at high temperatures.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTKD Analysis of Tribo\u0026ndash;layers and Plastic Deformation Layers With Nano\u0026ndash;heterostructures.\u003c/strong\u003e Compared with conventional electron backscatter diffraction (EBSD), the coaxial transmission kikuchi diffraction (TKD) technique offers a significantly improved pattern quality and resolution. To obtain the grain orientation, local misorientation, and recrystallization information of the tribo\u0026ndash;layer and subsurface, the tribo\u0026ndash;layer and subsurface of NiAlTa/cBN composites were analyzed by the TKD technique. Some regions could not be identified by TKD, which could be attributed to small grain size or amorphization. Figure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea and Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eb show the tribo\u0026ndash;layers and sub\u0026ndash;surfaces of NiAlTa metal and cBN particle surfaces at room temperature, respectively. Figure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ea\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e, \u003cstrong\u003eFig.\u0026nbsp;6a\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e, and \u003cstrong\u003eFig.\u0026nbsp;6a\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e display the inverse pole Figureure (IPF map), local misorientation map (KAM map), and recrystallization map of the tribo\u0026ndash;layer of NiAlTa metal, respectively. The amorphous tribo\u0026ndash;layer is difficult to be analyzed because it cannot produce Kikuchi patterns. The crystal orientation of the \u0026beta;\u0026ndash;NiAl phase in the subsurface changes slightly. This indicates that the small friction shear strain causes a mild plastic deformation of the subsurface. This again demonstrates that the amorphous tribo\u0026ndash;layer on the surface adapts to the elastic\u0026ndash;plastic deformation induced by sliding wear. Low angle grain boundaries (LAGBs) are found (Fig. 6\u003cstrong\u003ea\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e), which evolve from dislocation walls formed by the accumulation and rearrangement of dislocations [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]. Geometrically necessary dislocations (GNDs) are generated to accommodate subsurface shear deformation. In addition, GNDs show high density at grain boundaries (Fig.\u0026nbsp;6\u003cstrong\u003ea\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e). This suggests that the deformation difference between the soft and hard phases of \u0026beta;\u0026ndash;NiAl\u0026ndash;(Ni, Al)Ta leads to a high density of GNDs at the interfaces, which significantly enhances the strain\u0026ndash;hardening ability of NiAlTa metals (heterogeneous deformation\u0026ndash;induced strain\u0026ndash;hardening) [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e]. Accumulated GNDs can induce strain distribution between soft and hard phases to accommodate elastic\u0026ndash;plastic deformation due to dynamic loading [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e]. Substrucured and deformed grains are found within the subsurface (Fig.\u0026nbsp;6\u003cstrong\u003ea\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFigure 6b\u003c/strong\u003e \u003csub\u003e\u0026nbsp;\u003cstrong\u003e1\u003c/strong\u003e\u0026nbsp;\u003c/sub\u003e and \u003cstrong\u003eFig.\u0026nbsp;6b\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e show the IPF and KAM maps of the tribo\u0026ndash;layer of cBN particles, respectively. The orientation changes around the cracks. Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e nanoparticles on the surface of the amorphous tribo\u0026ndash;layer exhibit random orientations. GNDs show high density in Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e nanoparticles and around cracks. This suggests that Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e particles play a load\u0026ndash;supporting and stress\u0026ndash;transferring role in sliding wear. The presence of strain gradients requires the storage of GNDs to maintain deformation compatibility. Compared with metals, dislocation movement in ceramics is inherently retarded, which is attributed to strong ionic and covalent bonding [\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e]. Therefore, high density GNDs are only found around cracks. Under high friction loads, the retardation of dislocation movement is highly susceptible to cracking of ceramic particles.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ec and Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003ed show the tribo\u0026ndash;layers and subsurfaces of NiAlTa metal and cBN particles at high temperatures, respectively. Figure\u0026nbsp;6\u003cstrong\u003ec\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e, \u003cstrong\u003eFig.\u0026nbsp;6c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e, and \u003cstrong\u003eFig.\u0026nbsp;6c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e demonstrate the IPF map, KAM map, and recrystallization map of the tribo\u0026ndash;layer of NiAlTa metal, respectively. The oxide grains within the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer and the subsurface both show random orientations. The random grain orientation makes the grain boundary energy barrier high, which can effectively hinder the crack extension. However, due to the minimal strain tolerance and high hardness, the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer also ruptures or breaks to eliminate plastic deformation energy in sliding wear. Severe dislocation\u0026ndash;mediated plastic deformation occurs in the subsurface, which is confirmed by plenty of high\u0026ndash;angle grain boundaries (HAGBs) and LAGBs. Severe plastic deformation (SPD) usually leads to crack nucleation. This is because the maximum tensile stress is at the outer surface of the actual contact area (at the trailing edge of the contact). Also, according to the Hamilton model of subsurface stresses under spherical contact, friction force shifts the maximum shear stress in the contact region towards the wear surface [\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]. The initial direction of crack extension is perpendicular to the wear surface driven by the maximum tensile stress. This is consistent with the observation in \u003cstrong\u003eFig.\u0026nbsp;6c\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e. The average size of grains in the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer is 100 nm. The grain size within the subsurface shows a gradient distribution (50 nm \u0026rarr; 220 nm) (Fig. 6\u003cstrong\u003ec\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e). The lack of dislocation sources inside the small grains, as well as the limited storage of dislocations inside the grains due to their small size, deprives the subsurface of strain\u0026ndash;hardening capacity. The strain\u0026ndash;hardening capacity is critical for maintaining the off\u0026ndash;domain plastic strain. The few dislocations in the subsurface prove this (Fig.\u0026nbsp;6\u003cstrong\u003ec\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e). In addition, due to the lack of a transition layer, the large size difference between the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer and the nanogradient layer in the subsurface inevitably causes delamination due to the concentration of friction stress. In high\u0026ndash;temperature sliding wear, the decrease in the stability of the subsurface leads to the delamination and peeling of the tribo\u0026ndash;layer resulting in a high wear rate. This is confirmed by the above evidence.\u003c/p\u003e\n\u003cp\u003eIn addition, heat and flow stress gradients lead to the formation of dislocation\u0026ndash;mediated ultrafine crystalline layers presenting a nanogradient structure. The grain refinement at the subsurface is mainly determined by dislocation activity. Dislocation entanglements are gradually transformed into LAGBs. Under the effect of plastic strain, relative sliding and rotation between the sub\u0026ndash;grains are generated, and eventually a gradient fine\u0026ndash;grained layer with HAGBs is formed. However, the continuous accumulation of plastic strain causes strain localization in the fine\u0026ndash;grain layer, which is prone to cracking at the metal/ceramic interface or defects in the subsurface. In contrast to the subsurface, high density GNDs are found within the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer (Fig. 6\u003cstrong\u003ec\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e). The density of GNDs is proportional to the strain gradient, which indicates a high strain near the surface. A large number of deformed grains are found within the ZrO\u003csub\u003e2\u003c/sub\u003e surface layer (Fig. 6\u003cstrong\u003ec\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e3\u003c/strong\u003e\u003c/sub\u003e). Besides deformed grains, recrystallized grains are found within the subsurface. Recrystallized grains are first nucleated in deformation bands with high deformation storage energy distributed densely at dislocations and subgrain boundaries [\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]. Subgrains in the deformation zones grow to become effective nuclei for recrystallization by consuming the surrounding high\u0026ndash;energy zone. The high temperature significantly accelerates the nucleation rate of dynamically recrystallized grains. Figure\u0026nbsp;6\u003cstrong\u003ed\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e1\u003c/strong\u003e\u003c/sub\u003e and \u003cstrong\u003eFig.\u0026nbsp;6d\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e show the IPF and KAM maps of the tribo\u0026ndash;layer of cBN particles, respectively. The subsurface of cBN particles undergoes a mild orientation change. When the critical shear stress approaches the theoretical shear of cBN particles, a local loss of lattice stability occurs. Dislocations begin to homogeneously or heterogeneously nucleate and microplastic deformation occurs [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e]. Meanwhile, at high stresses, the cBN particles undergo the FCC \u0026rarr; HCP phase transition, which is essential to maintain the stable microplasticity of the ceramic particles.\u003c/p\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eNiAlTa/cBN composites exhibit excellent wear resistance, which is attributed to the specific tribo\u0026ndash;layers with special nano\u0026ndash;heterostructures induced by stress and temperature. At room temperature, the extremely low wear rate and low COF of the composites are attributed to the formation of an amorphous tribo\u0026ndash;layer. The nanograins undergo solid\u0026ndash;state amorphization induced by plastic deformation. O and Zr atoms promote the amorphization process. At high temperatures, strain localization of the oxide fine\u0026ndash;crystalline layer with nanogradient structure increases the wear rate of the composites. Meanwhile, the tribo\u0026ndash;induced amorphous oxide layer and oxidative cleaving effect decrease the fracture toughness of cBN particles and increase the wear rate. Tribo\u0026ndash;induced phase transition of cBN particles (fccBN \u0026rarr; hcpBN) and tribo\u0026ndash;chemical reaction of Ta with cBN are observed. Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e nanoparticles generated by tribo\u0026ndash;chemical reaction play a load\u0026ndash;supporting and stress\u0026ndash;transferring role in sliding wear. In addition, dislocations, faults networks, and the FCC \u0026rarr; HCP phase transition synergistically improve the strain\u0026ndash;hardening ability of cBN particles and reduce the wear rate. In conclusion, the intrinsic structure of NiAlTa/cBN composites relies on multiple deformation pathways of NiAlTa metals and cBN ceramics to induce tribo\u0026ndash;layers with specific nano\u0026ndash;heterostructures, thus adapting to the gradient elastic\u0026ndash;plastic strain distributed along the friction interface to achieve excellent wear resistance.\u003c/p\u003e"},{"header":"EXPERIMENTAL SECTION/METHODS","content":"\u003cp\u003e \u003cb\u003eComposites preparation.\u003c/b\u003e Ni\u0026ndash;coated cBN particles with a weight ratio of 25% were added to NiAlTa alloy powder (45Ni\u0026ndash;45Al\u0026ndash;10Ta, at%). NiAlTa/cBN composite blocks (Φ\u0026thinsp;=\u0026thinsp;30 mm, h\u0026thinsp;=\u0026thinsp;10 mm) were prepared by spark plasma sintering (1280\u0026deg;C, 50 MPa, and 30 min) after ball milling (300 rpm/min and 4 h). Several rectangles (30 \u0026times; 10 \u0026times; 4 mm) were removed from the NiAlTa/cBN composite block by a diamond wire saw. The rectangles were grinded with diamond disks; then they were polished with Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e polishing paste; finally, the polished samples were ultrasonically cleaned in alcohol.\u003c/p\u003e \u003cp\u003e \u003cb\u003eSliding wear experiments.\u003c/b\u003e Dry sliding wear experiments were conducted by an MTF\u0026ndash;5000 tribometer (Rtec, USA) equipped with a ball\u0026ndash;on\u0026ndash;plate reciprocating module. The plate was the NiAlTa/cBN composite. The ball was a ZrO\u003csub\u003e2\u003c/sub\u003e ceramic ball (Φ\u0026thinsp;=\u0026thinsp;9.525 mm). The reason for choosing ZrO\u003csub\u003e2\u003c/sub\u003e ceramic balls is to simulate the ZrO\u003csub\u003e2\u003c/sub\u003e ceramic\u0026ndash;based abradable coating on the turbine case surface, which rubs against the turbine blades or blade tip protective coating. Speed and displacement were fixed. Temperature and load were used as independent variables to investigate the dry sliding wear behavior of NiAlTa/cBN composites (Temperature 25 ℃, 500 ℃, and 1000 ℃; Load 10 N, 50 N, and 100 N; Sliding speed 0.02 m/s; Time 3600 s; Displacement 10 mm). The experimental temperature is slightly higher than the nominal experimental temperature due to friction heat generation [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Each set of experiments was repeated three times.\u003c/p\u003e \u003cp\u003e \u003cb\u003eCharacterization methods.\u003c/b\u003e The wear morphology and elemental composition of NiAlTa/cBN composites were analyzed by a MIRA3 field emission scanning electron microscope (SEM, TESCAN) equipped with an Ultim MaxN silicon drift type energy dispersive spectrometer (EDS). A D/Max\u0026ndash;2500PC X\u0026ndash;ray diffractometer (XRD, Cu Kα, 5 \u0026deg;/min, 20\u0026deg;~90\u0026deg;) and a field emission transmission electron microscope (TEM, Thermofisher Talos F200X) were utilized to determine the phase composition of the composites. The distribution of cBN particles in the composites was characterized by a microscopic computed tomography (CT). The CT data was processed using AVIZO software. The (nano)hardness and elastic modulus of the composites were determined by a TIME6610AT digital microhardness tester (Beijing Times Peak Science and Technology Co., Ltd., China, load 0.5 N) and a nanoindenter (Agilent TechnologiesNano Indenter G200, Agilent, USA, indentation depth 1000 nm). The average of five measurements was recorded. The two\u0026ndash;dimensional wear profile and three\u0026ndash;dimensional wear morphology of the wear scar were obtained by applying a 2300A\u0026ndash;R contact profilometer (Harbin Gauge and Sharpening Tools Group Co., Ltd., diamond stylus with a radius of 2 \u0026micro;m, highest resolution of 10 nm) and a VHX\u0026ndash;6000 ultra depth\u0026ndash;of\u0026ndash;field three\u0026ndash;dimensional microscope system (OM, Keyence, Japan). The wear rates of the composites under different experimental conditions were calculated according to Eq.\u0026nbsp;\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e \u003cp\u003eWhere \u003cem\u003eW\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e is the wear rate, mm\u003csup\u003e3\u003c/sup\u003e\u0026middot;N\u003csup\u003e\u0026ndash;1\u003c/sup\u003e\u0026middot;m\u003csup\u003e\u0026ndash;1\u003c/sup\u003e; \u003cem\u003eS\u003c/em\u003e is the average cross\u0026ndash;sectional area of the wear scar, mm\u003csup\u003e2\u003c/sup\u003e; \u003cem\u003ed\u003c/em\u003e is the length of the wear scar, mm; \u003cem\u003eP\u003c/em\u003e is the load, N; and \u003cem\u003eL\u003c/em\u003e is the sliding distance, m. The microscopic morphology, dislocations, grain orientation, local misorientation, and recrystallization of the tribo\u0026ndash;layers and subsurfaces of the composites were analyzed by a TEM equipped with an EDS and a high\u0026ndash;resolution coaxial transmission kikuchi diffraction (TKD, Bruker, with a step size of 10 nm). TEM and TKD samples were prepared using a dual beam focused ion beam (FIB, Thermo Scientific Scios 2). Small\u0026ndash;beam cutting and low\u0026ndash;voltage cleaning were employed to accurately obtain the intrinsically true structure to avoid crack formation. The FIB sampling direction was parallel to the sliding direction. Pt coating was deposited before FIB sampling to protect the worn surface. TKD data was processed by the HKL Channel 5 software (Oxford).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of Interest\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eY.S. carried out the experiments and wrote the paper; G.S. and D.D. designed the project and the material; Y.S., X.W., and W.B. conducted data analysis; Y.S. and D.D. designed the project and analyzed the wear mechanism. All authors contributed to the discussion of the results.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThis work is financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB 047010204) and the Tribology Science Fund of the State Key Laboratory of Tribology in Advanced Equipment (SKLTKF24B03).\u003c/p\u003e\u003ch2\u003eData Availability Statement\u003c/h2\u003e \u003cp\u003eThe data are available on request from the corresponding author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLou M et al (2021) Temperature\u0026ndash;induced wear transition in ceramic\u0026ndash;metal composites. Acta Mater 205:116545\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCheng Q et al (2022) Microstructure evolution and wear mechanism of in situ prepared Ti\u0026ndash;TiN cermet layers at high temperature. 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Surf Coat Tech 457:129316\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeng J et al (2024) Impact of gradient microstructure on strain hardening via activation of multiple deformation mechanisms in CoCrNi medium entropy alloy. Mater Futures 3:041002\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHamilton GM (1983) Explicit equations for the stresses beneath a sliding spherical contact. P I Mech Eng C\u0026ndash;J Mec 197:53\u0026ndash;59\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShetty DK et al (1985) Indentation fracture of WC\u0026ndash;Co cermets. J Mater Sci 20:1873\u0026ndash;1882\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRau JS et al (2021) High diffusivity pathways govern massively enhanced oxidation during tribological sliding. Acta Mater 221:117353\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiang J et al (1998) The role of triboparticulates in dry sliding wear. Tribol Int 31:245\u0026ndash;256\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eErdemir A (2000) A crystal\u0026ndash;chemical approach to lubrication by solid oxides. Tribol Lett 8:97\u0026ndash;102\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGeng Y et al (2023) Remarkable wear resistance in a complex concentrated alloy with nanohierarchical architecture and composition undulation. Research 6:0160\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSachdev H et al (1997) Investigation of the c\u0026ndash;BN/h\u0026ndash;BN phase transformation at normal pressure. Diam Relat Mater 6:286\u0026ndash;292\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYin C et al (2019) Formation of a self\u0026ndash;lubricating layer by oxidation and solid\u0026ndash;state amorphization of nano\u0026ndash;lamellar microstructures during dry sliding wear tests. 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Shanghai Jiaotong Univ Press 183\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"advanced-composites-and-hybrid-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"achm","sideBox":"Learn more about [Advanced Composites and Hybrid Materials](https://link.springer.com/journal/42114)","snPcode":"42114","submissionUrl":"https://submission.nature.com/new-submission/42114/3","title":"Advanced Composites and Hybrid Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Nano–heterostructures, NiAlTa/cBN composites, Wear resistance, Wear mechanism, Tribo–layer","lastPublishedDoi":"10.21203/rs.3.rs-6275026/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6275026/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe study of the evolution of nano–heterostructures controlling tribological behavior is crucial for optimizing the wear resistance of composites. A novel NiAlTa/cBN composite produced by spark plasma sintering exhibited exceptional wear resistance, which is attributed to the tribo–layers with special nano–heterostructures induced by stress and temperature. At room temperature, an extremely low wear rate (10\u003csup\u003e–7\u003c/sup\u003e mm\u003csup\u003e3\u003c/sup\u003e·N\u003csup\u003e–1\u003c/sup\u003e·m\u003csup\u003e–1\u003c/sup\u003e) and a low coefficient of friction (0.252) of the composite were attributed to the nanoscale amorphous tribo–layer. Amorphization was synergistically controlled by the plastic deformation–induced solid–state amorphization and oxidation processes. Tribo–induced amorphous layer accommodated the sliding–induced elastic–plastic deformation and virtually eliminated wear. At high temperatures, the plastic incompatibility and strain localization of the subsurface nanocrystalline layer mediated by dislocations, stacking faults, and deformation twins increased the wear rate. The formation of an amorphous tribo–oxide layer and oxidative cleaving effect reduced the fracture toughness of cBN particles and increased the tendency of crack nucleation and growth. Dislocations, stacking fault networks, and FCC → HCP phase transition synergistically increased the microplastic deformability and strain–hardening capacity of cBN particles and reduced the wear rate. Ta\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e5\u003c/sub\u003e nanoparticles generated by tribo–chemical reaction played a load–supporting and stress–transferring role in sliding wear. This work highlighted the significance of the tribo–induced evolution of the tribo–layers on the wear resistance of the composite. A strategy to achieve exceptional wear resistance by regulating the evolution of specific nano–heterostructures on the composite surfaces was proposed.\u003c/p\u003e","manuscriptTitle":"Tribo–Driven Evolution of Specific Nano–heterostructures to Achieve Exceptional Wear Resistance in Composites","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-03-27 08:25:07","doi":"10.21203/rs.3.rs-6275026/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-29T01:54:52+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-27T07:26:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"253962643527190223612250292729088115096","date":"2025-05-23T01:18:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"232336212577062435878612792009977770856","date":"2025-05-22T12:26:12+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-21T11:38:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"117248765722319329751757986518705398360","date":"2025-04-14T10:57:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"252808745858044620822933301706787176938","date":"2025-04-12T22:18:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-09T01:50:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-08T11:42:47+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-04-03T14:30:48+00:00","index":"","fulltext":""},{"type":"submitted","content":"Advanced Composites and Hybrid Materials","date":"2025-03-21T07:08:17+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"advanced-composites-and-hybrid-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"achm","sideBox":"Learn more about [Advanced Composites and Hybrid Materials](https://link.springer.com/journal/42114)","snPcode":"42114","submissionUrl":"https://submission.nature.com/new-submission/42114/3","title":"Advanced Composites and Hybrid Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"55393ccd-ed77-48e0-86cb-6c5093da684c","owner":[],"postedDate":"March 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-01T16:07:51+00:00","versionOfRecord":{"articleIdentity":"rs-6275026","link":"https://doi.org/10.1007/s42114-025-01415-w","journal":{"identity":"advanced-composites-and-hybrid-materials","isVorOnly":false,"title":"Advanced Composites and Hybrid Materials"},"publishedOn":"2025-08-28 15:57:57","publishedOnDateReadable":"August 28th, 2025"},"versionCreatedAt":"2025-03-27 08:25:07","video":"","vorDoi":"10.1007/s42114-025-01415-w","vorDoiUrl":"https://doi.org/10.1007/s42114-025-01415-w","workflowStages":[]},"version":"v1","identity":"rs-6275026","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6275026","identity":"rs-6275026","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}