Features of joint structure formation between Kovar and stainless steel using Cu-Mn-Co(Fe) brazing alloy

Features of joint structure formation between Kovar and stainless steel using Cu-Mn-Co(Fe) brazing alloy | 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 Features of joint structure formation between Kovar and stainless steel using Cu-Mn-Co(Fe) brazing alloy Svitlana Maksymova, Petro Kovalchuk, Vitalii Voronov This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5930833/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract The study presents the results of research on the structural formation characteristics of brazed joints between Kovar and corrosion-resistant steel when using brazing alloys of the Cu-Mn-4.5Co-(Fe) system. These characteristics were analyzed depending on the alloy composition and the size of the brazing gap. Metallographic and micro-X-ray spectral studies of dissimilar brazed joints revealed that the use of Cu-Mn-4.5Co and Cu-Mn-Co-2.5Fe alloys results in the formation of joint structures with morphologies that differ significantly from the initial state of the brazing alloys. In both cases, the brazed joints contain a solid solution based on the copper-manganese system. The difference lies in the phases formed: when using the Cu-Mn-4.5Co alloy, a manganese-based phase enriched with iron is formed, whereas the Cu-Mn-Co-2.5Fe alloy leads to the formation of an iron-based phase. It was demonstrated that reducing the brazing gap increases the amount of γ-phase Fe x (Mn y Co z Me), in the joint when using Cu-Mn-4.5Co-2.5Fe, which positively affects the mechanical properties of the joints. This improvement is evidenced by the fracture of samples occurring in the base metal, namely, the corrosion-resistant steel. Cu-Mn-Co-Fe brazing filler metal brazing gap structure strength high-temperature vacuum brazing solid solution Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1 Introduction The current requirements for engineering structures and assemblies demand that they simultaneously satisfy the stringent criteria of material and energy efficiency, operational reliability, and economic feasibility. These demands highlight one of the most pressing challenges in modern manufacturing—the development of effective technologies for joining dissimilar materials [ 1 , 2 ]. Particular attention is drawn to the combination of austenitic stainless steel, which is distinguished by its exceptional strength, ductility, and corrosion resistance, with other materials. Such dissimilar joints are increasingly being utilized in various industrial fields, demonstrating their versatility and potential for solving complex engineering problems [ 1 , 3 – 5 ]. The joining of stainless steel with other materials, such as Kovar, is accomplished using a variety of methods, including fusion welding techniques (such as electron beam and laser welding), diffusion welding, and brazing [ 6 – 14 ]. Among these, vacuum brazing has established itself as a preferred method for the production of critical components, owing to the inherent cleanliness of the process and the ability to minimize contamination from external sources. This method is particularly valued in high-tech industries such as nuclear power and aerospace, where stringent performance and reliability standards must be met [ 1 , 14 – 15 ]. Brazing, as a thermodynamically driven process, involves the melting of a filler metal that wets the solid surface of the base material and interacts with it chemically. This interaction at the solid-liquid interface is of paramount importance, as it determines the microstructure and ultimately the mechanical and technological properties of the brazed joint [ 16 – 18 ]. At this interface, various structural components can form, including intermetallic phases and diffusion zones, which ensure a strong metallurgical bond. These structural elements have a direct and critical impact on the joint's mechanical strength, durability, and operational performance [ 17 ]. When joining dissimilar materials, the complex diffusion processes occurring during brazing can sometimes lead to undesirable changes. These may include alterations in the composition of the brazing alloy, the formation of depleted zones within the alloy, and the appearance of brittle intermetallic compounds or eutectic phases in the joint [ 1 ]. These phenomena can significantly affect the quality and durability of the brazed joint. Consequently, selecting a brazing alloy with an appropriate melting temperature range is critical but not sufficient. The joint's properties are also strongly influenced by a combination of metallurgical factors (e.g., alloy composition), technological parameters (e.g., heating regime), and geometric characteristics (e.g., gap size and surface topography) [ 6 , 18 , 19 ]. Variations in these factors can arise under practical conditions, including inconsistencies in material compositions, irregularities in the brazing gap, and surface defects, making their careful optimization essential. One of the key parameters influencing the success of the vacuum brazing process is the brazing gap size. The gap size plays a decisive role in determining the uniformity of filler metal distribution within the joint, the formation of the brazed seam structure, and the resultant mechanical properties of the joint. Proper optimization of this parameter ensures not only a defect-free seam but also maximized joint strength. This is particularly crucial when joining dissimilar materials, where the presence of even minor defects can compromise the integrity of the joint under operational conditions [ 18 , 19 – 21 ]. The primary goal of this study is to conduct a detailed investigation into the influence of the brazing alloy composition, as well as the diffusion processes and brazing gap size, on the microstructure and mechanical properties of joints between Kovar and stainless steel. These joints were fabricated through high-temperature vacuum brazing using a Cu-Mn-Co-(Fe)-based alloy, with the aim of optimizing brazing parameters to enhance the performance and reliability of such dissimilar material assemblies. 2 Investigation methods and materials For the experiments, Kovar precision alloy and 12Kh18N10T stainless steel (Table 1 ) were used as the base metals. Table 1 Chemical composition of Kovar and steel 12Kh18N10T [ 22 ] Grade Chemical elements, wt. % Fe Ni Co C Si Mn Cr Ti Al Cu Kovar 51.14–54.50 28.50–29.50 17.00–18.00 0.03 0.30 0.40 0.10 0.10 0.20 0.20 12Kh18N10T 67.00 9.00–1.00 - 0.12 0.80 2.00 17.00–19.00 0,40 − 1.00 - 0.30 Filler metal 1 - - 4,50 - - 32,00 - - - rest Filler metal 2 2,50 - 4,50 - - 32,00 - - - rest The experimental brazing filler metal in its cast state was produced by argon arc melting using a non-consumable tungsten electrode on a cold copper substrate in a high-purity argon atmosphere. To obtain a homogeneous structure and ensure uniform distribution of alloying elements throughout the brazing filler metal, a five-time remelting process with ingot inversion was performed. Before brazing, the base metal sample blanks were mechanically processed, degreased with gasoline, and dehydrated using technical alcohol. High-temperature brazing was carried out in a vacuum furnace (SGV 2.4-2/15-I3) with radiation heating, under a vacuum of 1.33×10 − 3 Pa. The heating rate did not exceed 18–20°C/min, and the cooling rate in the temperature range from 1060°C to 200°C was 10–15°C/min, with a temperature measurement accuracy of ± 5°C. The brazing temperature was determined based on preliminary studies [ 23 ], and it did not exceed the brazing filler metal's liquidus temperature by more than 30°C, with a holding time of 3 minutes. Vacuum brazing of samples of dissimilar joints between Kovar and corrosion-resistant steel was carried out with both constant and variable gaps ranging from 0 to 1 mm (Fig. 1 ). Prior to brazing, the sample was secured in a clamp. For mechanical testing, lap joint samples were made from dissimilar materials, measuring 80×15×2 mm (three samples for each gap size), with an overlap corresponding to the thickness of the plates. The brazed samples for metallographic analysis were cut perpendicular to the joint and microsections were prepared following standard procedures. Metallographic studies and micro-X-ray spectral analysis were carried out using a TescanMira 3 LMU scanning electron microscope. The local elemental distribution in individual phases was examined via micro-X-ray spectral analysis using an Oxford Instruments X-max 80-mm² energy dispersive spectrometer. The sections were examined without chemical etching in backscattered electron (BSE) mode. The localization accuracy of the measurements was up to 1 µm. The mechanical properties of the brazed lap joints were tested at room temperature using a ZDM 10 Zwick-1488 testing machine. The phase composition percentage was determined by analyzing SEM images using ImageJ software, with an error margin of ± 1.5%. 3 Results and Discussion Metallographic analysis of the brazed joints (Fig. 2a) revealed that using Cu-Mn-4.5Co as the brazing alloy results in a seam structure whose morphology (Fig. 2b) differs significantly from that of the alloy in its original state [24]. Micro-X-ray spectral analysis of the elemental distribution in local areas of the brazed joint showed that, in a wide brazed seam (~1 mm), dendrites of a manganese-based phase Mn(CoCuFe) crystallize within the copper solid solution matrix. These dendrites contain a small concentration of chromium (Fig. 2 c, Table 2, Spectrum 2). Table 2 Distribution of elements in the brazed seam Kovar – corrosion-resistant steel Spectrum No Chemical elements, wt. % Si Ti Cr Mn Fe Co Ni Cu 1 0.00 0.00 2.10 38.53 13.62 27.06 0.00 18.68 2 0.00 0.00 1.03 36.88 9.11 21.86 2.19 28.93 3 0.12 0.00 0.12 25.47 0.34 2.80 3.51 67.64 4 0.38 0.35 17.23 1.13 67.06 0.43 13.41 0.00 On the side of the base metal, at the interfacial boundary between the stainless steel and the brazing alloy, fine-grained manganese-based phases Mn(CoFeCu) were identified. These phases exhibited elevated cobalt (27.06%) and iron (13.62%) concentrations (Fig. 3 c, Table 2, Spectrum 1). It is noteworthy that the copper content in these grains decreases from 28.93% to 18.68%. An analysis of the elemental distribution in the Kovar-stainless steel joint, performed by scanning the brazed seam cross-section with an electron beam, confirmed the presence of a phase based on the Mn-Co-Fe system in the brazed seam (Fig. 3 a, b, c, d). The results of electron beam scanning perpendicular to the brazed seam align well with previous studies, confirming the increased manganese concentration in specific phases. Based on the results of micro X-ray spectral studies, it can be concluded that during the formation of the brazed joint structure, active mutual diffusion processes occur between the elements of the filler metal and the base material, particularly iron, cobalt, nickel, chromium, and manganese. The heating temperature influences these processes, the non-equilibrium conditions during the crystallization of the brazed joint metal, and the chemical composition of the base material and filler, leading to the formation of a concentration gradient at the interface between the filler metal and the base material. A schematic representation of the structure formation in the brazed joint metal can be proposed, as shown in Fig. 4. During heating, the brazing filler metal melts and forms a liquid phase. The diffusion of base metal components, particularly iron, into the molten brazing filler metal begins in the first seconds [25] upon the formation of the liquid phase. As the metal in the brazed joint becomes saturated with iron, an iron-enriched phase begins to form and grow. To improve the mechanical properties of the brazed joints, the experimental Cu-Mn-4.5Co brazing alloy was modified by alloying 2.5 wt. % of iron. The findings from local X-ray microspectral analysis confirmed the two-phase composition of the seam. The main phase is a homogeneous Cu-Mn solid solution that includes trace amounts of nickel, iron, and cobalt. The second phase consists of discrete dark grains of an iron-based γ-phase Fe x (Mn y Co z Me), which also incorporates other elements from both the brazing filler metal and the base metal. Figure 5 shows the microstructures of Kovar–stainless steel brazed joints with brazing gaps ranging from 100 µm to 20 µm. Reducing the brazing gap from 100 µm to 20 µm when brazing dissimilar joints of Kovar and corrosion-resistant steel not only decreases the width of the brazed joint but also leads to significant morphological changes in the structure and chemical composition of the phases during the crystallization of the brazed joint metal (Fig. 5). The main phase constitutes 86.83% of the total seam area at a brazing gap of 100 μm (Fig. 5a). At an initial gap of 50 μm, the structure is represented by a copper-manganese solid solution, but its proportion slightly decreases compared to the previous sample (Fig. 5a), amounting to 82.25% of the total seam area. Based on the research results, there is a noticeable reduction of the amount of the Cu-Mn solid solution in the brazed joint. At a gap of 20 μm, it constitutes only 9.10% of the total seam area. Furthermore, the data from local X-ray microspectral analysis reveal significant differences in the chemical composition of the individual phases compared to previous samples. In particular, the concentration of iron in the solid solution increases to approximately 6.39% as the brazing gap size decreases to 20 μm. Fig. 6 shows the chemical composition of the γ-phase Fe x (Mn y Co z Me), and the α-(Cu-Mn) solid solution as a function of the brazing gap size. Additionally, the studies conducted in this work have demonstrated that the structure and morphological characteristics of the brazed joints' metal in Kovar-stainless steel dissimilar joints, using a Cu-Mn-Co-Fe filler metal, primarily depend on the width of the brazing gap, which influences the diffusion processes. It has been empirically proven that increasing the gap size negatively affects the mechanical properties of the brazed joints (Table 3), which can be explained by the aforementioned structural features of the brazed seams. The brazed samples with a minimum brazing gap of 20 μm demonstrate the highest strength (600 MPa), with failure occurring primarily in the base metal - stainless steel along with minor plastic deformation. Table 3. Strength of brazed joints Kovar - stainless steel depending on the gap size (at 20°C) Filler metal Brazing gap size, μm τ s , MPa σ b, MPa Fracture site Cu-Mn-4,5Co 20 434 - seam Cu-Mn-Co-2,5Fe 20 - 580-635 12Kh18N10T 50 498-505 - seam 100 408-459 - seam This finding highlight that the strength of a dissimilar joint formed through brazing exceeds that of stainless steel after undergoing a high-temperature vacuum brazing process. The data clearly show that the size of the brazing gap influences the seam morphology, the chemical composition of its phases, and the mechanical properties of the brazed joints. The results of the investigation confirm the correlation between the structural characteristics of brazed seams and their strength. 4 Conclusions Metallographic and micro-X-ray spectral studies of brazed dissimilar joints between Kovar and corrosion-resistant steel have shown that using Cu-Mn-4.5Co and Cu-Mn-Co-2.5Fe alloys results in the formation of joint structures with morphologies differing significantly from the initial state of the brazing alloys. In both cases, the brazed joints contain a solid solution based on the copper-manganese system. The distinction lies in the phases formed: with the Cu-Mn-4.5Co alloy, a manganese-based phase enriched with iron is observed, while with the Cu-Mn-Co-2.5Fe alloy, an iron-based phase is formed. Based on the obtained data, it has been established that the size of the brazing gap influences the joint's morphology, the chemical composition of individual phases, and the mechanical properties of the brazed joints. Metallographic studies confirmed the formation of a two-phase structure in the brazed joints, consisting of an α-(Cu-Mn) solid solution and grains of the γ-phase Fe x (Mn y Co z Me), The volume ratio of these phases changes with the gap size. Reducing the gap size from 100 µm to 20 µm leads to a decrease in the amount of the solid solution from 86.83–9.10% and a corresponding increase in the γ-phase content from 13.17–90.90%. Furthermore, the iron concentration in the γ-phase rises from 32.58–46.13%. In the α-(Cu-Mn) solid solution, reducing the gap size slightly increases the iron content from 1.12–6.39%. Experimental results demonstrated that alloying the Cu-Mn-4.5Co brazing alloy with 2.5% iron enhances the shear strength of the brazed joints by 33–38%. Mechanical tests further revealed that reducing the brazing gap from 100 µm to 50 µm increases the shear strength of the brazed joints from 408–459 MPa to 498–505 MPa. When the gap size is reduced to 20 µm, the strength reaches 600 MPa. At this gap size, fracture occurs in the base metal (stainless steel) with minimal plastic deformation, which can be attributed to the structural characteristics of the brazed joints. Declarations Data Availability Statement The data that support the findings of this study are available from the corresponding author upon reasonable request. Authors Contribution Svitlana Maksymova: Conceptualization, Investigation, Formal analysis, Writing original draft, Editing. Petro Kovalchuk: Investigation, Formal analysis, Processing of research results. Vitalii Voronov: Investigation, Writing original draft, Formal analysis, Editing. Funding This work was financially supported by the by the National Academy of Sciences of Ukraine. Follow the decision of the Department of Materials Science of the National Academy of Sciences of Ukraine (grant number 0122U002197). Competing interests The authors declare that they have known no competing financial interest or personal relationships that could have appeared to influence the work reported in this paper. References Beura VK, Xavier V, Venkateswaran T, Kulkarni KN (2018) Interdiffusion and microstructure evolution during brazing of austenitic martensitic stainless steel and aluminum-bronze with Ag-Cu-Zn based brazing filler material. J. Alloys Compd. 740:852-862 https://doi.org/10.1016/j.jallcom.2018.01.043. Robert J, Messler W (2000) Joining of Materials and Structures: From Pragmatic Process to Enabling Technology. Elsevier, Burlington Garion C, Skoczeń B, Sgobba S (2006) Constitutive modelling and identification of parameters of the plastic strain-induced martensitic transformation in 316L stainless steel at cryogenic temperatures. Int. J. Plasticity, 22(7):1234–1264. https://doi.org/10.1016/j.ijplas.2005.08.002 Reed R, Horiuchi T (1983) Austenitic steels at low temperatures. Plenum Press, New York Rudenko LF, Govorun TP (2012) Alloy steels and alloys. Sumy state university, Sumy Jing Y, Ren X, Shang Y, Xiong H, Jiang J (2021) Develop a novel high-strength vacuum brazing technique for γ-TiAl intermetallic. International Journal of Lightweight Materials and Manufacture 4(2):237-245. https://doi.org/10.1016/j.ijlmm.2020.11.002 Sabetghadam H, Hanzaki AZ, Araee A (2010) Diffusion bonding of 410 stainless steel to copper using a nickel interlayer, Mater. Charact. 61(6):626–634. https://doi.org/10.1016/j.matchar.2010.03.006 Magnabosco I, Ferro P, Bonollo F, Arnberg L (2006) An investigation of fusion zone microstructures in electron beam welding of copper-stainless steel. Mater. Sci. Eng. A. 424(1-2):163–173. https://doi.org/10.1016/j.msea.2006.03.096 Zheng Y, Li N, Yan J, Cao Y (2016) The microstructure and mechanical properties of 1Cr17Ni2/QAl7 brazed joints using Cu-Mn-Ni-Ag brazing alloy. Mater. Sci. Eng. A. 661:25–31. https://doi.org/10.1016/j.msea.2016.03.020 Baghjari SH, Gholambargani M, Akbari Mousavi SAA (2019) Application of the Pulsed Nd: YAG Laser Welding to Investigate the Effect of Laser Beam Position on Weld Characteristics of AISI 420 Stainless Steel to Kovar Alloy Lasers Manuf. Mater. Process. 6:14–25. https://doi.org/10.1007/s40516-018-0078-y Fadhali MMA, Zainal SJ, Munajat Y, Jalil A, Rahman R (2009) Abstr. AIP Conf. Proc. (29 May – 1 June, 2009, Langkawi, Kedah, Malaysia: 147-152 Kaletina YuV, Efimova ED, Romanov MK (2014) Problems of weldability of parts made of austenitic steel 12X18N10T and precision alloy 29NK. Metallovedenie i termicheskaya obrabotka metallov 6:26 Feng J, Herrmann M, Reinecke A-M, Hurtado A (2024) Active Brazing for Energy Devices Sealing. J. Exp. Theor. Anal., 2(1):1-27 https://doi.org/10.3390/jeta2010001 Song T, Jiang X, Shao Z, Mo D, Zhu D Zhu M (2016) The Interfacial Microstructure and Mechanical Properties of Diffusion-Bonded Joints of 316L Stainless Steel and the 4J29 Kovar Alloy Using Nickel as an Interlayer. Metals 6:263. https://doi.org/10.3390/met6110263 Jacobson D, Humpston G (2005) Principles of brazing, first ed., ASM International, Materials Park, Ohio Ma C, Xue S, Wang B (2016) Study on novel Ag-Cu-Zn-Sn brazing filler metal bearing Ga, J. Alloys Compd. 688(B):854–862. https://doi.org/10.1016/j.jallcom.2016.07.255 Laik A, Shirzadi AA, Tewari R, Kumar A, Jayakumar T, Dey GK (2013) Microstructure and Interfacial Reactions During Active Metal Brazing of Stainless Steel to Titanium. Metall Mater Trans A 44:2212–2225. https://doi.org/10.1007/s11661-012-1599-1 Jöckel A, Baumgartner J, Tillmann W, Bültena J, Bobzin K, Heinemann H, Hebing J, Erck M (2022) Influence of brazing process and gap size on the fatigue strength of shear and peel specimen. Weld. World 66:1941–1955. https://doi.org/10.1007/s40194-022-01304-6 Maksymova SV, Khorunov VF Voronov VV (2013) Effect of gap value and initial state of brazing alloy of structure formation of titanium alloy brazed joints. The Paton Weld. J. 3:28-33 Ermolaev GV, Kvasnitsky VV, Kvasnitsky VF, Maksymova SV, Khorunov VF, Chigarov VV (2015) Metal brazing Textbook. NUK, Mykolaiv Radziievskyi VM, Budnyk AF, Yuskaiev VB (2011) Metallurgy of high-temperature technology of non-separable joints. Sumy State University, Sumy Shishkov MM (2002) Brands of steels and alloys. Directory. Yugo-Vostok, Donetsk Maksymova SV, Kovalchuk PV, Voronov VV, Datsіuk II (2023) The influence of iron on the structure and technological characteristics of Cu-Mn-Co-Fe brazing filler metal. The Paton Welding J. 8:36-43. https://doi.org/10.37434/tpwj2023.08.04 Maksymova SV, Kovalchuk PV, Voronov VV (2019) Influence of Cobalt on the Structure and Technological Properties of Alloys of the Cu-Mn System. Metallofiz. Noveishie Tekhnol. 41(10):1365-1003. https://doi.org/10.15407/mfint.41.10.1365 Maksymova SV (2023) Influence of Diffusion Processes on the Structure of Brazed Joints of Titanium Aluminides. Current Topics and Emerging Issues in Materials Sciences 2:14–29. https://doi.org/10.9734/bpi/cteims/v2/5554A Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 19 Feb, 2025 Reviewers invited by journal 06 Feb, 2025 Editor invited by journal 05 Feb, 2025 Editor assigned by journal 03 Feb, 2025 First submitted to journal 30 Jan, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5930833","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":412022103,"identity":"8b295aeb-e6d5-460d-89fd-f1edab959946","order_by":0,"name":"Svitlana Maksymova","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-0158-5760","institution":"Institut elektrozvaruvanna imeni E O Patona Nacional'na akademia nauk Ukraini","correspondingAuthor":true,"prefix":"","firstName":"Svitlana","middleName":"","lastName":"Maksymova","suffix":""},{"id":412022104,"identity":"c9911adf-e291-4b3e-acd4-f88c3e67f659","order_by":1,"name":"Petro Kovalchuk","email":"","orcid":"","institution":"Institut elektrozvaruvanna imeni E O Patona Nacional'na akademia nauk Ukraini","correspondingAuthor":false,"prefix":"","firstName":"Petro","middleName":"","lastName":"Kovalchuk","suffix":""},{"id":412022105,"identity":"3c382e2e-8ee9-4988-9290-962cdcea7fb5","order_by":2,"name":"Vitalii Voronov","email":"","orcid":"","institution":"Institut elektrozvaruvanna imeni E O Patona Nacional'na akademia nauk Ukraini","correspondingAuthor":false,"prefix":"","firstName":"Vitalii","middleName":"","lastName":"Voronov","suffix":""}],"badges":[],"createdAt":"2025-01-30 14:08:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5930833/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5930833/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":75896388,"identity":"fba54dcf-2960-4482-94bc-b8f825f155ce","added_by":"auto","created_at":"2025-02-10 10:33:44","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":190319,"visible":true,"origin":"","legend":"\u003cp\u003eScheme of sample fixation in a clamp: 1 - ceramic substrates; 2 - corrosion-resistant steel; 3 - brazing alloy; 4 - Kovar; 5 - gap spacer (ceramic, 1 mm thick)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5930833/v1/283ce2f23af7b740987a9ce0.png"},{"id":75896392,"identity":"a9dba4ba-d613-4ef8-9afa-75fd1395e4c1","added_by":"auto","created_at":"2025-02-10 10:33:45","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1063403,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructure of the brazed dissimilar joint between Kovar and corrosion-resistant steel: (a) general view; (b) structure of the brazed joint; (c) areas where the chemical composition was analyzed\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5930833/v1/e32a2006aa5111d49aaaeef5.png"},{"id":75896355,"identity":"b2134a8a-f6ee-46e1-ab0a-5dda8090784e","added_by":"auto","created_at":"2025-02-10 10:33:43","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":461003,"visible":true,"origin":"","legend":"\u003cp\u003eElectron image (a) and distribution of constituent elements: (b) iron; (c) cobalt; (d) chromium; (e) copper; (f) manganese; obtained during beam scanning of the brazed joint between Kovar and corrosion-resistant steel\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-5930833/v1/e29428cb0015e1fa9467023f.png"},{"id":75897715,"identity":"6cc642ad-7b88-44e4-bc8f-fc601436f39e","added_by":"auto","created_at":"2025-02-10 10:41:43","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":513542,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of samples before (a) and during brazing (b)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-5930833/v1/f076ca589f305104e2ab0238.png"},{"id":75896396,"identity":"8f4d33c3-478d-43e2-9322-861cc4cb3736","added_by":"auto","created_at":"2025-02-10 10:33:45","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1415550,"visible":true,"origin":"","legend":"\u003cp\u003eMicrostructures of the Kovar - stainless steel brazed joints at a gap size of 100 μm (a), 50 μm (b) and 20 μm (c)\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-5930833/v1/c2a1d28414949684ff7c8c1b.png"},{"id":75897721,"identity":"6ccb1590-f097-4b69-ae6b-ea00ea60514b","added_by":"auto","created_at":"2025-02-10 10:41:43","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":535371,"visible":true,"origin":"","legend":"\u003cp\u003eChemical composition of the γ-phase Fe\u003csub\u003ex\u003c/sub\u003e(Mn\u003csub\u003ey\u003c/sub\u003eCo\u003csub\u003ez\u003c/sub\u003eMe), (a) and the α-(Cu-Mn) solid solution (b) as a function of the brazing gap size\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-5930833/v1/96773b707b39402dbfdcf892.png"},{"id":75899996,"identity":"af6aa148-ba1e-4aad-b6ca-c1185828f983","added_by":"auto","created_at":"2025-02-10 10:57:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4766388,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5930833/v1/9370a990-b8ad-44b9-9f75-67c0c65d440d.pdf"}],"financialInterests":"","formattedTitle":"Features of joint structure formation between Kovar and stainless steel using Cu-Mn-Co(Fe) brazing alloy","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eThe current requirements for engineering structures and assemblies demand that they simultaneously satisfy the stringent criteria of material and energy efficiency, operational reliability, and economic feasibility. These demands highlight one of the most pressing challenges in modern manufacturing\u0026mdash;the development of effective technologies for joining dissimilar materials [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Particular attention is drawn to the combination of austenitic stainless steel, which is distinguished by its exceptional strength, ductility, and corrosion resistance, with other materials. Such dissimilar joints are increasingly being utilized in various industrial fields, demonstrating their versatility and potential for solving complex engineering problems [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe joining of stainless steel with other materials, such as Kovar, is accomplished using a variety of methods, including fusion welding techniques (such as electron beam and laser welding), diffusion welding, and brazing [\u003cspan additionalcitationids=\"CR7 CR8 CR9 CR10 CR11 CR12 CR13\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Among these, vacuum brazing has established itself as a preferred method for the production of critical components, owing to the inherent cleanliness of the process and the ability to minimize contamination from external sources. This method is particularly valued in high-tech industries such as nuclear power and aerospace, where stringent performance and reliability standards must be met [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eBrazing, as a thermodynamically driven process, involves the melting of a filler metal that wets the solid surface of the base material and interacts with it chemically. This interaction at the solid-liquid interface is of paramount importance, as it determines the microstructure and ultimately the mechanical and technological properties of the brazed joint [\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. At this interface, various structural components can form, including intermetallic phases and diffusion zones, which ensure a strong metallurgical bond. These structural elements have a direct and critical impact on the joint's mechanical strength, durability, and operational performance [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhen joining dissimilar materials, the complex diffusion processes occurring during brazing can sometimes lead to undesirable changes. These may include alterations in the composition of the brazing alloy, the formation of depleted zones within the alloy, and the appearance of brittle intermetallic compounds or eutectic phases in the joint [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. These phenomena can significantly affect the quality and durability of the brazed joint. Consequently, selecting a brazing alloy with an appropriate melting temperature range is critical but not sufficient. The joint's properties are also strongly influenced by a combination of metallurgical factors (e.g., alloy composition), technological parameters (e.g., heating regime), and geometric characteristics (e.g., gap size and surface topography) [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Variations in these factors can arise under practical conditions, including inconsistencies in material compositions, irregularities in the brazing gap, and surface defects, making their careful optimization essential.\u003c/p\u003e \u003cp\u003eOne of the key parameters influencing the success of the vacuum brazing process is the brazing gap size. The gap size plays a decisive role in determining the uniformity of filler metal distribution within the joint, the formation of the brazed seam structure, and the resultant mechanical properties of the joint. Proper optimization of this parameter ensures not only a defect-free seam but also maximized joint strength. This is particularly crucial when joining dissimilar materials, where the presence of even minor defects can compromise the integrity of the joint under operational conditions [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe primary goal of this study is to conduct a detailed investigation into the influence of the brazing alloy composition, as well as the diffusion processes and brazing gap size, on the microstructure and mechanical properties of joints between Kovar and stainless steel. These joints were fabricated through high-temperature vacuum brazing using a Cu-Mn-Co-(Fe)-based alloy, with the aim of optimizing brazing parameters to enhance the performance and reliability of such dissimilar material assemblies.\u003c/p\u003e"},{"header":"2 Investigation methods and materials","content":"\u003cp\u003eFor the experiments, Kovar precision alloy and 12Kh18N10T stainless steel (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) were used as the base metals.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eChemical composition of Kovar and steel 12Kh18N10T [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eGrade\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"10\" nameend=\"c11\" namest=\"c2\"\u003e \u003cp\u003eChemical elements, wt. %\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFe\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNi\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCo\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSi\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMn\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eCr\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eTi\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eAl\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKovar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e51.14\u0026ndash;54.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.50\u0026ndash;29.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e17.00\u0026ndash;18.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.20\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e12Kh18N10T\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.00\u0026ndash;1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e17.00\u0026ndash;19.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0,40\u0026thinsp;\u0026minus;\u0026thinsp;1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003e0.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFiller metal 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4,50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e32,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003erest\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFiller metal 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2,50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4,50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e32,00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e \u003cp\u003erest\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe experimental brazing filler metal in its cast state was produced by argon arc melting using a non-consumable tungsten electrode on a cold copper substrate in a high-purity argon atmosphere. To obtain a homogeneous structure and ensure uniform distribution of alloying elements throughout the brazing filler metal, a five-time remelting process with ingot inversion was performed.\u003c/p\u003e \u003cp\u003eBefore brazing, the base metal sample blanks were mechanically processed, degreased with gasoline, and dehydrated using technical alcohol. High-temperature brazing was carried out in a vacuum furnace (SGV 2.4-2/15-I3) with radiation heating, under a vacuum of 1.33\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e Pa. The heating rate did not exceed 18\u0026ndash;20\u0026deg;C/min, and the cooling rate in the temperature range from 1060\u0026deg;C to 200\u0026deg;C was 10\u0026ndash;15\u0026deg;C/min, with a temperature measurement accuracy of \u0026plusmn;\u0026thinsp;5\u0026deg;C. The brazing temperature was determined based on preliminary studies [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], and it did not exceed the brazing filler metal's liquidus temperature by more than 30\u0026deg;C, with a holding time of 3 minutes.\u003c/p\u003e \u003cp\u003eVacuum brazing of samples of dissimilar joints between Kovar and corrosion-resistant steel was carried out with both constant and variable gaps ranging from 0 to 1 mm (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Prior to brazing, the sample was secured in a clamp.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor mechanical testing, lap joint samples were made from dissimilar materials, measuring 80\u0026times;15\u0026times;2 mm (three samples for each gap size), with an overlap corresponding to the thickness of the plates.\u003c/p\u003e \u003cp\u003eThe brazed samples for metallographic analysis were cut perpendicular to the joint and microsections were prepared following standard procedures. Metallographic studies and micro-X-ray spectral analysis were carried out using a TescanMira 3 LMU scanning electron microscope. The local elemental distribution in individual phases was examined via micro-X-ray spectral analysis using an Oxford Instruments X-max 80-mm\u0026sup2; energy dispersive spectrometer. The sections were examined without chemical etching in backscattered electron (BSE) mode. The localization accuracy of the measurements was up to 1 \u0026micro;m.\u003c/p\u003e \u003cp\u003eThe mechanical properties of the brazed lap joints were tested at room temperature using a ZDM 10 Zwick-1488 testing machine. The phase composition percentage was determined by analyzing SEM images using ImageJ software, with an error margin of \u0026plusmn;\u0026thinsp;1.5%.\u003c/p\u003e"},{"header":"3 Results and Discussion","content":"\u003cp\u003eMetallographic analysis of the brazed joints (Fig. 2a) revealed that using Cu-Mn-4.5Co as the brazing alloy results in a seam structure whose morphology (Fig. 2b) differs significantly from that of the alloy in its original state [24].\u003c/p\u003e\n\u003cp\u003eMicro-X-ray spectral analysis of the elemental distribution in local areas of the brazed joint showed that, in a wide brazed seam (~1 mm), dendrites of a manganese-based phase Mn(CoCuFe) crystallize within the copper solid solution matrix. These dendrites contain a small concentration of chromium (Fig. 2 c, Table 2, Spectrum 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u003c/strong\u003e Distribution of elements in the brazed seam Kovar \u0026ndash; corrosion-resistant steel\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eSpectrum No\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"8\" valign=\"top\"\u003e\n \u003cp\u003eChemical elements, wt. %\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eTi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCr\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMn\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eFe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNi\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCu\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e38.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e27.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e18.68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e36.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e9.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e21.86\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.19\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e28.93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e25.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e2.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3.51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e67.64\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e17.23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e67.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e13.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eOn the side of the base metal, at the interfacial boundary between the stainless steel and the brazing alloy, fine-grained manganese-based phases Mn(CoFeCu) were identified. These phases exhibited elevated cobalt (27.06%) and iron (13.62%) concentrations (Fig. 3 c, Table 2, Spectrum 1). It is noteworthy that the copper content in these grains decreases from 28.93% to 18.68%.\u003c/p\u003e\n\u003cp\u003eAn analysis of the elemental distribution in the Kovar-stainless steel joint, performed by scanning the brazed seam cross-section with an electron beam, confirmed the presence of a phase based on the Mn-Co-Fe system in the brazed seam (Fig. 3 a, b, c, d).\u003c/p\u003e\n\u003cp\u003eThe results of electron beam scanning perpendicular to the brazed seam align well with previous studies, confirming the increased manganese concentration in specific phases. Based on the results of micro X-ray spectral studies, it can be concluded that during the formation of the brazed joint structure, active mutual diffusion processes occur between the elements of the filler metal and the base material, particularly iron, cobalt, nickel, chromium, and manganese. The heating temperature influences these processes, the non-equilibrium conditions during the crystallization of the brazed joint metal, and the chemical composition of the base material and filler, leading to the formation of a concentration gradient at the interface between the filler metal and the base material. A schematic representation of the structure formation in the brazed joint metal can be proposed, as shown in Fig. 4.\u003c/p\u003e\n\u003cp\u003eDuring heating, the brazing filler metal melts and forms a liquid phase. The diffusion of base metal components, particularly iron, into the molten brazing filler metal begins in the first seconds [25] upon the formation of the liquid phase. As the metal in the brazed joint becomes saturated with iron, an iron-enriched phase begins to form and grow.\u003c/p\u003e\n\u003cp\u003eTo improve the mechanical properties of the brazed joints, the experimental Cu-Mn-4.5Co brazing alloy was modified by alloying 2.5 wt. % of iron.\u003c/p\u003e\n\u003cp\u003eThe findings from local X-ray microspectral analysis confirmed the two-phase composition of the seam. The main phase \u0026nbsp;is a homogeneous Cu-Mn solid solution that includes trace amounts of nickel, iron, and cobalt. The second phase consists of discrete dark grains of an iron-based \u0026gamma;-phase Fe\u003csub\u003ex\u003c/sub\u003e(Mn\u003csub\u003ey\u003c/sub\u003eCo\u003csub\u003ez\u003c/sub\u003eMe), which also incorporates other elements from both the brazing filler metal and the base metal.\u003c/p\u003e\n\u003cp\u003eFigure 5 shows the microstructures of Kovar\u0026ndash;stainless steel brazed joints with brazing gaps ranging from 100 \u0026micro;m to 20 \u0026micro;m. \u0026nbsp;Reducing the brazing gap from 100 \u0026micro;m to 20 \u0026micro;m when brazing dissimilar joints of Kovar and corrosion-resistant steel not only decreases the width of the brazed joint but also leads to significant morphological changes in the structure and chemical composition of the phases during the crystallization of the brazed joint metal (Fig. 5).\u003c/p\u003e\n\u003cp\u003eThe main phase constitutes 86.83% of the total seam area at a brazing gap of 100 \u0026mu;m (Fig. 5a). At an initial gap of 50 \u0026mu;m, the structure is represented by a copper-manganese solid solution, but its proportion slightly decreases compared to the previous sample (Fig. 5a), amounting to 82.25% of the total seam area. Based on the research results, there is a noticeable reduction of the amount of the Cu-Mn solid solution in the brazed joint. At a gap of 20 \u0026mu;m, it constitutes only 9.10% of the total seam area.\u003c/p\u003e\n\u003cp\u003eFurthermore, the data from local X-ray microspectral analysis reveal significant differences in the chemical composition of the individual phases compared to previous samples. In particular, the concentration of iron in the solid solution increases to approximately 6.39% as the brazing gap size decreases to 20 \u0026mu;m.\u003c/p\u003e\n\u003cp\u003eFig. 6 shows the chemical composition of the \u0026gamma;-phase Fe\u003csub\u003ex\u003c/sub\u003e(Mn\u003csub\u003ey\u003c/sub\u003eCo\u003csub\u003ez\u003c/sub\u003eMe), and the \u0026alpha;-(Cu-Mn) solid solution as a function of the brazing gap size.\u003c/p\u003e\n\u003cp\u003eAdditionally, the studies conducted in this work have demonstrated that the structure and morphological characteristics of the brazed joints\u0026apos; metal in Kovar-stainless steel dissimilar joints, using a Cu-Mn-Co-Fe filler metal, primarily depend on the width of the brazing gap, which influences the diffusion processes.\u003c/p\u003e\n\u003cp\u003eIt has been empirically proven that increasing the gap size negatively affects the mechanical properties of the brazed joints (Table 3), which can be explained by the aforementioned structural features of the brazed seams.\u003c/p\u003e\n\u003cp\u003eThe brazed samples with a minimum brazing gap of 20 \u0026mu;m demonstrate the highest strength (600 MPa), with failure occurring primarily in the base metal - stainless steel along with minor plastic deformation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;3.\u003c/strong\u003e Strength of brazed joints Kovar - stainless steel depending on the gap size (at 20\u0026deg;C)\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eFiller metal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eBrazing gap size, \u0026mu;m\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026tau;\u003csub\u003es\u003c/sub\u003e, MPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u0026sigma;\u003csub\u003eb,\u0026nbsp;\u003c/sub\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eFracture site\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCu-Mn-4,5Co\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e434\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eseam\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\"\u003e\n \u003cp\u003eCu-Mn-Co-2,5Fe\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e580-635\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e12Kh18N10T\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e498-505\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eseam\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e408-459\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eseam\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThis finding highlight that the strength of a dissimilar joint formed through brazing exceeds that of stainless steel after undergoing a high-temperature vacuum brazing process. The data clearly show that the size of the brazing gap influences the seam morphology, the chemical composition of its phases, and the mechanical properties of the brazed joints. The results of the investigation confirm the correlation between the structural characteristics of brazed seams and their strength.\u003c/p\u003e"},{"header":"4 Conclusions","content":"\u003cp\u003eMetallographic and micro-X-ray spectral studies of brazed dissimilar joints between Kovar and corrosion-resistant steel have shown that using Cu-Mn-4.5Co and Cu-Mn-Co-2.5Fe alloys results in the formation of joint structures with morphologies differing significantly from the initial state of the brazing alloys. In both cases, the brazed joints contain a solid solution based on the copper-manganese system. The distinction lies in the phases formed: with the Cu-Mn-4.5Co alloy, a manganese-based phase enriched with iron is observed, while with the Cu-Mn-Co-2.5Fe alloy, an iron-based phase is formed.\u003c/p\u003e \u003cp\u003eBased on the obtained data, it has been established that the size of the brazing gap influences the joint's morphology, the chemical composition of individual phases, and the mechanical properties of the brazed joints. Metallographic studies confirmed the formation of a two-phase structure in the brazed joints, consisting of an α-(Cu-Mn) solid solution and grains of the γ-phase Fe\u003csub\u003ex\u003c/sub\u003e(Mn\u003csub\u003ey\u003c/sub\u003eCo\u003csub\u003ez\u003c/sub\u003eMe), The volume ratio of these phases changes with the gap size. Reducing the gap size from 100 \u0026micro;m to 20 \u0026micro;m leads to a decrease in the amount of the solid solution from 86.83\u0026ndash;9.10% and a corresponding increase in the γ-phase content from 13.17\u0026ndash;90.90%. Furthermore, the iron concentration in the γ-phase rises from 32.58\u0026ndash;46.13%. In the α-(Cu-Mn) solid solution, reducing the gap size slightly increases the iron content from 1.12\u0026ndash;6.39%.\u003c/p\u003e \u003cp\u003eExperimental results demonstrated that alloying the Cu-Mn-4.5Co brazing alloy with 2.5% iron enhances the shear strength of the brazed joints by 33\u0026ndash;38%. Mechanical tests further revealed that reducing the brazing gap from 100 \u0026micro;m to 50 \u0026micro;m increases the shear strength of the brazed joints from 408\u0026ndash;459 MPa to 498\u0026ndash;505 MPa. When the gap size is reduced to 20 \u0026micro;m, the strength reaches 600 MPa. At this gap size, fracture occurs in the base metal (stainless steel) with minimal plastic deformation, which can be attributed to the structural characteristics of the brazed joints.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSvitlana Maksymova: Conceptualization, Investigation, Formal analysis, Writing original draft, Editing.\u003c/p\u003e\n\u003cp\u003ePetro Kovalchuk: Investigation, Formal analysis, Processing of research results.\u003c/p\u003e\n\u003cp\u003eVitalii Voronov: \u003csup\u003e\u0026nbsp;\u003c/sup\u003eInvestigation, Writing \u0026nbsp;original draft, Formal analysis, Editing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was financially supported by the by the National Academy of Sciences of Ukraine. Follow the decision of the Department of Materials Science of the National Academy of Sciences of Ukraine (grant number 0122U002197).\u003cstrong\u003e\u003cu\u003e\u0026nbsp;\u003c/u\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have known no competing financial interest or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBeura VK, Xavier V, Venkateswaran T, Kulkarni KN (2018) Interdiffusion and microstructure evolution during brazing of austenitic martensitic stainless steel and aluminum-bronze with Ag-Cu-Zn based brazing filler material. J. Alloys Compd. 740:852-862 https://doi.org/10.1016/j.jallcom.2018.01.043. \u003c/li\u003e\n\u003cli\u003eRobert J, Messler W (2000) Joining of Materials and Structures: From Pragmatic Process to Enabling Technology. Elsevier, Burlington \u003c/li\u003e\n\u003cli\u003eGarion C, Skoczeń B, Sgobba S (2006) Constitutive modelling and identification of parameters of the plastic strain-induced martensitic transformation in 316L stainless steel at cryogenic temperatures. Int. J. Plasticity, 22(7):1234\u0026ndash;1264. https://doi.org/10.1016/j.ijplas.2005.08.002 \u003c/li\u003e\n\u003cli\u003eReed R, Horiuchi T (1983) Austenitic steels at low temperatures. Plenum Press, New York \u003c/li\u003e\n\u003cli\u003eRudenko LF, Govorun TP (2012) Alloy steels and alloys. Sumy state university, Sumy \u003c/li\u003e\n\u003cli\u003eJing Y, Ren X, Shang Y, Xiong H, Jiang J (2021) Develop a novel high-strength vacuum brazing technique for \u0026gamma;-TiAl intermetallic. International Journal of Lightweight Materials and Manufacture 4(2):237-245. https://doi.org/10.1016/j.ijlmm.2020.11.002 \u003c/li\u003e\n\u003cli\u003eSabetghadam H, Hanzaki AZ, Araee A (2010) Diffusion bonding of 410 stainless steel to copper using a nickel interlayer, Mater. Charact. 61(6):626\u0026ndash;634. https://doi.org/10.1016/j.matchar.2010.03.006 \u003c/li\u003e\n\u003cli\u003eMagnabosco I, Ferro P, Bonollo F, Arnberg L (2006) An investigation of fusion zone microstructures in electron beam welding of copper-stainless steel. Mater. Sci. Eng. A. 424(1-2):163\u0026ndash;173. https://doi.org/10.1016/j.msea.2006.03.096 \u003c/li\u003e\n\u003cli\u003eZheng Y, Li N, Yan J, Cao Y (2016) The microstructure and mechanical properties of 1Cr17Ni2/QAl7 brazed joints using Cu-Mn-Ni-Ag brazing alloy. Mater. Sci. Eng. A. 661:25\u0026ndash;31. https://doi.org/10.1016/j.msea.2016.03.020 \u003c/li\u003e\n\u003cli\u003eBaghjari SH, Gholambargani M, Akbari Mousavi SAA (2019) Application of the Pulsed Nd: YAG Laser Welding to Investigate the Effect of Laser Beam Position on Weld Characteristics of AISI 420 Stainless Steel to Kovar Alloy Lasers Manuf. Mater. Process. 6:14\u0026ndash;25. https://doi.org/10.1007/s40516-018-0078-y \u003c/li\u003e\n\u003cli\u003eFadhali MMA, Zainal SJ, Munajat Y, Jalil A, Rahman R (2009) Abstr. AIP Conf. Proc. (29 May \u0026ndash; 1 June, 2009, Langkawi, Kedah, Malaysia: 147-152 \u003c/li\u003e\n\u003cli\u003eKaletina YuV, Efimova ED, Romanov MK (2014) Problems of weldability of parts made of austenitic steel 12X18N10T and precision alloy 29NK. Metallovedenie i termicheskaya obrabotka metallov 6:26 \u003c/li\u003e\n\u003cli\u003eFeng J, Herrmann M, Reinecke A-M, Hurtado A (2024) Active Brazing for Energy Devices Sealing. J. Exp. Theor. Anal., 2(1):1-27 https://doi.org/10.3390/jeta2010001 \u003c/li\u003e\n\u003cli\u003eSong T, Jiang X, Shao Z, Mo D, Zhu D Zhu M (2016) The Interfacial Microstructure and Mechanical Properties of Diffusion-Bonded Joints of 316L Stainless Steel and the 4J29 Kovar Alloy Using Nickel as an Interlayer. Metals 6:263. https://doi.org/10.3390/met6110263 \u003c/li\u003e\n\u003cli\u003eJacobson D, Humpston G (2005) Principles of brazing, first ed., ASM International, Materials Park, Ohio\u003c/li\u003e\n\u003cli\u003eMa C, Xue S, Wang B (2016) Study on novel Ag-Cu-Zn-Sn brazing filler metal bearing Ga, J. Alloys Compd. 688(B):854\u0026ndash;862. https://doi.org/10.1016/j.jallcom.2016.07.255 \u003c/li\u003e\n\u003cli\u003eLaik A, Shirzadi AA, Tewari R, Kumar A, Jayakumar T, Dey GK (2013) Microstructure and Interfacial Reactions During Active Metal Brazing of Stainless Steel to Titanium. Metall Mater Trans A 44:2212\u0026ndash;2225. https://doi.org/10.1007/s11661-012-1599-1 \u003c/li\u003e\n\u003cli\u003eJ\u0026ouml;ckel A, Baumgartner J, Tillmann W, B\u0026uuml;ltena J, Bobzin K, Heinemann H, Hebing J, Erck M (2022) Influence of brazing process and gap size on the fatigue strength of shear and peel specimen. Weld. World 66:1941\u0026ndash;1955. https://doi.org/10.1007/s40194-022-01304-6 \u003c/li\u003e\n\u003cli\u003eMaksymova SV, Khorunov VF Voronov VV (2013) Effect of gap value and initial state of brazing alloy of structure formation of titanium alloy brazed joints. The Paton Weld. J. 3:28-33 \u003c/li\u003e\n\u003cli\u003eErmolaev GV, Kvasnitsky VV, Kvasnitsky VF, Maksymova SV, Khorunov VF, Chigarov VV (2015) Metal brazing Textbook. NUK, Mykolaiv\u003c/li\u003e\n\u003cli\u003eRadziievskyi VM, Budnyk AF, Yuskaiev VB (2011) Metallurgy of high-temperature technology of non-separable joints. Sumy State University, Sumy\u003c/li\u003e\n\u003cli\u003eShishkov MM (2002) Brands of steels and alloys. Directory. Yugo-Vostok, Donetsk\u003c/li\u003e\n\u003cli\u003eMaksymova SV, Kovalchuk PV, Voronov VV, Datsіuk II (2023) The influence of iron on the structure and technological characteristics of Cu-Mn-Co-Fe brazing filler metal. The Paton Welding J. 8:36-43. https://doi.org/10.37434/tpwj2023.08.04 \u003c/li\u003e\n\u003cli\u003eMaksymova SV, Kovalchuk PV, Voronov VV (2019) Influence of Cobalt on the Structure and Technological Properties of Alloys of the Cu-Mn System. Metallofiz. Noveishie Tekhnol. 41(10):1365-1003. https://doi.org/10.15407/mfint.41.10.1365 \u003c/li\u003e\n\u003cli\u003eMaksymova SV (2023) Influence of Diffusion Processes on the Structure of Brazed Joints of Titanium Aluminides. Current Topics and Emerging Issues in Materials Sciences 2:14\u0026ndash;29. https://doi.org/10.9734/bpi/cteims/v2/5554A \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"welding-in-the-world","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"witw","sideBox":"Learn more about [Welding in the World](https://www.springer.com/journal/40194)","snPcode":"40194","submissionUrl":"https://www.editorialmanager.com/witw/","title":"Welding in the World","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Cu-Mn-Co-Fe brazing filler metal, brazing gap, structure, strength, high-temperature vacuum brazing, solid solution","lastPublishedDoi":"10.21203/rs.3.rs-5930833/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5930833/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe study presents the results of research on the structural formation characteristics of brazed joints between Kovar and corrosion-resistant steel when using brazing alloys of the Cu-Mn-4.5Co-(Fe) system. These characteristics were analyzed depending on the alloy composition and the size of the brazing gap. Metallographic and micro-X-ray spectral studies of dissimilar brazed joints revealed that the use of Cu-Mn-4.5Co and Cu-Mn-Co-2.5Fe alloys results in the formation of joint structures with morphologies that differ significantly from the initial state of the brazing alloys. In both cases, the brazed joints contain a solid solution based on the copper-manganese system. The difference lies in the phases formed: when using the Cu-Mn-4.5Co alloy, a manganese-based phase enriched with iron is formed, whereas the Cu-Mn-Co-2.5Fe alloy leads to the formation of an iron-based phase. It was demonstrated that reducing the brazing gap increases the amount of γ-phase Fe\u003csub\u003ex\u003c/sub\u003e(Mn\u003csub\u003ey\u003c/sub\u003eCo\u003csub\u003ez\u003c/sub\u003eMe), in the joint when using Cu-Mn-4.5Co-2.5Fe, which positively affects the mechanical properties of the joints. This improvement is evidenced by the fracture of samples occurring in the base metal, namely, the corrosion-resistant steel.\u003c/p\u003e","manuscriptTitle":"Features of joint structure formation between Kovar and stainless steel using Cu-Mn-Co(Fe) brazing alloy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-10 10:33:37","doi":"10.21203/rs.3.rs-5930833/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-02-19T08:35:33+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-02-06T10:30:25+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Welding in the World","date":"2025-02-05T23:57:03+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-02-03T13:29:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"Welding in the World","date":"2025-01-31T04:45:40+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"welding-in-the-world","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"witw","sideBox":"Learn more about [Welding in the World](https://www.springer.com/journal/40194)","snPcode":"40194","submissionUrl":"https://www.editorialmanager.com/witw/","title":"Welding in the World","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ed232779-9b87-4050-b6b2-216185143d68","owner":[],"postedDate":"February 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-05-12T20:53:33+00:00","versionOfRecord":[],"versionCreatedAt":"2025-02-10 10:33:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5930833","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5930833","identity":"rs-5930833","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}