Multi-element ti-based medium-entropy alloy brazing filler metal, application and brazing method thereof

Abstract

The application relates to the technical field of aviation brazing, and provides a multi-element Ti-based middle-entropy alloy filler metal, which comprises the following components in percentage by weight: Mn: 16.0-22.0%, Fe: 12.0-18.0%, Ni: 2.0-8.0%, Co: 2.0-8.0%, V: 1.0-7.0%, Cr: 0-6.0%, and Ti: the balance. The application also provides application of the middle-entropy alloy filler metal and a brazing method of a TiAl alloy. The filler metal can realize brazing of the TiAl at 1180-1190 DEG C, the tensile strength of a brazed joint at room temperature reaches 479-508 MPa, the strength coefficient is 0.81-0.86; the tensile strength at 700 DEG C reaches 514-524 MPa, the tensile strength at 750 DEG C reaches 495-521 MPa, the tensile strength at 850 DEG C reaches 396-418 MPa, and the strength coefficient in a wide range of 700-850 DEG C is basically stable at more than 0.85.

Description

Technical Field

[0001] This invention relates to the field of aerospace brazing technology, and in particular to a multi-component Ti-based medium-entropy alloy brazing filler metal, its application and brazing method. Background Technology

[0002] The main advantages of TiAl-based alloys lie in their low density (3.9~4.2 g / cm³), high specific strength and specific stiffness, and excellent creep resistance, oxidation resistance, and flame retardancy below 800℃. In the aerospace field, parts made from TiAl-based alloys can withstand long-term operating temperatures of 700~850℃, significantly improving the long-term service temperature of components compared to titanium alloys. Furthermore, compared to traditional nickel-based superalloys, TiAl-based alloys have lower density and higher specific strength. Therefore, TiAl-based alloys have broad prospects for high-temperature applications in the aerospace field.

[0003] However, TiAl-based alloys are inherently brittle, with only 1-3% room temperature plasticity, making them highly susceptible to cracking during welding. From a feasibility and cost-effectiveness perspective, brazing is a highly suitable joining technique for TiAl-based alloys. Current research on TiAl-based alloy brazing technology focuses on improvements in brazing methods, brazing filler metals, brazing processes, brazing process control, and room temperature / high temperature strength of brazed joints. However, the brazing temperature of the filler metal and the strength of the brazed joint remain inconsistent.

[0004] Ag-based or Al-based brazing alloys have low brazing temperatures, but their high-temperature joint strength is significantly insufficient. Although Ti-based brazing alloys have improved room-temperature joint strength, their high-temperature strength remains insufficient, and some Ti-based brazing alloys require very high brazing temperatures, such as exceeding 1200℃, which can easily damage the base material. Therefore, the key to TiAl-based alloy brazing alloy research lies in achieving brazing at lower temperatures (below 1200℃) while simultaneously ensuring high room-temperature / high-temperature (750~850℃) strength in the brazed joint. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a multi-element Ti-based medium-entropy alloy brazing filler metal, which can effectively solve the problems of excessively high brazing temperature and insufficient room temperature / high temperature (750~850℃) strength of brazed joints in TiAl alloy brazing, reduce the brazing temperature and improve the room temperature / high temperature (750~850℃) strength of the brazed joints.

[0006] In view of this, this application provides a multi-component Ti-based medium-entropy alloy solder, characterized in that, by mass percentage, it comprises:

[0007] Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 2.0~8.0%, Co: 2.0~8.0%, V: 1.0~7.0%, Cr: 0~6.0%, Ti: balance.

[0008] Preferably, the medium-entropy alloy brazing filler metal comprises: Mn: 17.0~21.0%, Fe: 13.0~17.0%, Ni: 2.5~7.5%, Co: 2.5~7.5%, V: 1.5~6.5%, Cr: 0.5~5.5%, and Ti: balance.

[0009] Preferably, the method for preparing the medium-entropy alloy solder includes the following steps:

[0010] A) Prepare the alloy ingot by mixing the materials according to the mass percentage of the multi-component Ti-based medium-entropy alloy solder and then melting them.

[0011] B) Prepare the alloy ingot into medium-entropy alloy brazing filler metals for different applications.

[0012] Preferably, the multi-element Ti-based medium-entropy alloy solder is used in one or more of the following forms: molten alloy block, molten alloy fragments, molten alloy sheet, molten alloy powder, quenched foil strip, and powder sintered body.

[0013] This application also provides the application of the aforementioned multi-element Ti-based medium-entropy alloy brazing filler metal in brazing connections of Ti-based materials.

[0014] This application also provides a brazing method for TiAl alloys, comprising the following steps:

[0015] S1) Pre-treat the surface of the base material;

[0016] S2) Add brazing filler metal to the welding position of the base material obtained in step S1) to obtain the assembly;

[0017] S3) Brazing the assembly components;

[0018] The solder is the multi-component Ti-based medium-entropy alloy solder described in the above scheme.

[0019] Preferably, the brazing gap between the base materials in the assembly is 0.03~0.10mm.

[0020] Preferably, the brazing temperature is 1180~1190℃.

[0021] Preferably, the brazing method is vacuum brazing.

[0022] Preferably, the brazing specifically includes:

[0023] The assembly is placed in a vacuum brazing furnace and heated to 500-700°C at a rate of 10-40°C / min, then to 800-1000°C at a rate of 10-30°C / min, and then to 1180-1190°C at a rate of 10-25°C / min and held for 20-75 minutes. After the holding period, the assembly is cooled to room temperature at a rate of 10-40°C / min.

[0024] This application provides a multi-component Ti-based medium-entropy alloy brazing filler metal, comprising, by mass percentage: Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 2.0~8.0%, Co: 2.0~8.0%, V: 1.0~7.0%, Cr: 0~6.0%, and Ti: balance. This application incorporates more than five alloying elements into the medium-entropy alloy brazing filler metal. Fe and Mn elements refine the grain and provide solid solution strengthening, thereby improving the room temperature and high temperature mechanical properties of the TiAl joint; Ni element promotes dynamic recrystallization, improving the hot working plasticity of the TiAl joint; Co element refines the grain, improving the room temperature strength and plasticity of the TiAl joint, and also improving high-temperature oxidation performance; Cr element significantly improves the plasticity of the TiAl joint, and Cr, after coupling with Mn, significantly refines the grain, thus significantly improving the room temperature / high temperature strength and toughness of the TiAl joint; V element refines the grain and improves the strength and toughness of the TiAl alloy. Therefore, the brazing filler metal provided in this application comprehensively utilizes the solid solution strengthening and grain refinement strengthening effects of different elements to improve the strength of the brazed joint. Simultaneously, the addition of the aforementioned metallic elements to the filler metal can form multiple eutectic compositions such as Ti-Mn-Fe, Ti-Ni-Co, Ti-Co, and Ti-Ni, as well as multiple low-melting-point compositions such as Co-V(Cr), Ni-V(Cr), and Mn-Ni, resulting in a combined reduction in melting point. The actual liquidus of the filler metal is 1103.5~1113.2℃, thus allowing brazing within the range of 1180~1190℃, significantly reducing the brazing temperature. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the assembly structure in step S2 of the TiAl alloy brazing process of the present invention;

[0026] Figure 2 A photograph of the frontal morphology of TiAl alloy after brazing;

[0027] Figure 3 Micrograph of the cross-section of the brazed joint;

[0028] Figure 4 The Ti-Mn-Fe ternary phase diagram;

[0029] Figure 5 The Ti-Ni-Co ternary phase diagram;

[0030] Figure 6 The Fe-Mn-Ni ternary phase diagram;

[0031] Figure 7 The Fe-Mn-Co ternary phase diagram;

[0032] Figure 8 The Fe-Mn-Cr ternary phase diagram;

[0033] Figure 9 The Fe-Mn-V ternary phase diagram;

[0034] Figure 10 The Co-Ni-Cr ternary phase diagram;

[0035] Figure 11 The Co-Ni-V ternary phase diagram;

[0036] Figure 12 The Co-Ni-Mn ternary phase diagram;

[0037] Figure 13 The Cr-Ni-V ternary phase diagram;

[0038] Figure 14 The average high-temperature tensile strength curve of the brazed joint (650℃~850℃) is shown for the brazing filler metal of the present invention under the conditions of (1180~1190)℃ / (20-75)min. Detailed Implementation

[0039] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

[0040] In view of the low brazing temperature of existing TiAl-based alloy brazing filler metals and the requirement for room temperature / high temperature strength of brazed joints, this application provides a multi-element Ti-based medium-entropy alloy brazing filler metal. By introducing five or more metallic elements and adjusting their content, the brazing temperature of the filler metal is ultimately reduced, while the room temperature / high temperature strength of the brazed joint is improved. Specifically, this application provides a multi-element Ti-based medium-entropy alloy brazing filler metal, characterized in that, by mass percentage, it comprises:

[0041] Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 2.0~8.0%, Co: 2.0~8.0%, V: 1.0~7.0%, Cr: 0~6.0%, Ti: balance.

[0042] In the multi-component Ti-based medium-entropy alloy brazing filler metal of this application, Mn element can refine grains and strengthen through solid solution, thereby improving the room temperature and high temperature mechanical properties of TiAl alloy brazed joints. The Mn content is 16.0~22.0 wt%, specifically, the Mn content is 17.0~21.0 wt%, and more specifically, the Mn content is 16.0 wt%, 16.5 wt%, 17.5 wt%, 18.0 wt%, 18.5 wt%, 19.1 wt%, 19.5 wt%, 18.6 wt%, 20.0 wt%, 20.5 wt%, 21.0 wt%, 21.5 wt%, or 22.0 wt%.

[0043] Fe can also refine grains and strengthen through solid solution. The Fe content is 12.0~18.0 wt%, specifically 13.0~17.0 wt%, and more specifically, 12.0 wt%, 12.5 wt%, 13.0 wt%, 13.3 wt%, 13.8 wt%, 14.0 wt%, 14.2 wt%, 14.1 wt%, 14.6 wt%, 15.0 wt%, 15.2 wt%, 15.5 wt%, 15.7 wt%, 15.9 wt%, 16.0 wt%, 16.1 wt%, 16.5 wt%, 16.6 wt%, 17.0 wt%, 17.2 wt%, 17.5 wt%, 17.8 wt%, or 18.0 wt%.

[0044] Ni promotes dynamic recrystallization and improves the hot workability of TiAl joints. The Ni content is 2.0~8.0 wt%, specifically 2.5~7.5 wt%, and more specifically, 2.0 wt%, 2.5 wt%, 2.6 wt%, 3.0 wt%, 3.2 wt%, 3.5 wt%, 3.8 wt%, 4.0 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, 5.0 wt%, 5.3 wt%, 5.6 wt%, 5.9 wt%, 6.0 wt%, 6.3 wt%, 6.6 wt%, 6.8 wt%, 6.9 wt%, 7.0 wt%, 7.5 wt%, 7.8 wt%, or 8.0 wt%.

[0045] Co can refine grains, improve the room temperature strength and ductility of TiAl joints, and enhance high-temperature oxidation performance. The Co content is 2.0~8.0 wt%, specifically 2.5~7.5 wt%, and more specifically, 2.0 wt%, 2.2 wt%, 2.7 wt%, 3.0 wt%, 3.2 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 4.0 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, 5.0 wt%, 5.3 wt%, 5.6 wt%, 5.9 wt%, 6.0 wt%, 6.3 wt%, 6.6 wt%, 6.8 wt%, 6.9 wt%, 7.0 wt%, 7.5 wt%, 7.8 wt%, or 8.0 wt%.

[0046] V can refine grains and improve the strength and toughness of TiAl alloys. The V content is 1.0~7.0 wt%, specifically 1.5~6.5 wt%, and more specifically, the V content is 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.7 wt%, 2.0 wt%, 2.2 wt%, 2.7 wt%, 3.0 wt%, 3.2 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 4.0 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, 5.0 wt%, 5.3 wt%, 5.5 wt%, 5.6 wt%, 5.9 wt%, 6.0 wt%, 6.3 wt%, 6.6 wt%, 6.8 wt%, 6.9 wt%, and 7.0 wt%.

[0047] Cr significantly improves the plasticity of TiAl joints, and the coupling of Cr with Mn can significantly refine the grains, thereby significantly improving the room temperature / high temperature strength and toughness of TiAl joints. However, Cr should not be added in excess, otherwise it will increase the melting point. The Cr content is 0~6wt%, specifically 0.5~5.5wt%, more specifically, 0.1wt%, 0.3wt%, 0.5wt%, 1.0wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2.0wt%, 2.3wt%, 2.5wt%, 2.8wt%, 3.0wt%, 3.2wt%, 3.5wt%, 4.0wt%, 4.8wt%, 5.0wt%, 5.2wt%, 5.5wt%, 5.8wt%, or 6.0wt%.

[0048] This application uses either a Ti-Mn-Fe-Ni-Co-V-Cr seven-element medium-entropy alloy brazing filler metal or a Ti-Mn-Fe-Ni-Co-V six-element medium-entropy alloy brazing filler metal. The selection of elements was based on in-depth research and rational selection of elements and composition. Specifically: according to the Ti-Mn-Fe ternary phase diagram, Ti has good compatibility with Mn and Fe elements, and a ternary eutectic composition Ti-20Mn-18Fe (wt%) exists, with a eutectic temperature of approximately 1126℃. Furthermore, Ni, Co, V, and Cr are added to the Ti-Fe-Mn base to improve the high-temperature resistance of the brazing filler metal and the brazed joint. According to the Ti-Ni-Co ternary phase diagram, a ternary eutectic composition Ti-3Ni-22Co (wt%) exists, with a eutectic temperature of 1025℃. The Ti-Ni-Co eutectic composition can lower the alloy melting point. Furthermore, according to the Ti-Co binary phase diagram, a binary eutectic composition of Ti-26.7Co (wt%) exists, with a eutectic temperature of 1015℃. This Ti-Co eutectic composition can further lower the alloy's melting point. Additionally, according to the Ti-Ni binary phase diagram, a binary eutectic composition of Ti-28.4Ni (wt%) exists, with a eutectic temperature of 943℃. This Ti-Ni eutectic composition can further lower the alloy's melting point. Furthermore, according to the Mn-Ni binary phase diagram, a low-melting-point composition of Mn-41.6Ni (wt%) exists, with a corresponding temperature of 1020℃. Co, Ni, and Cr exhibit good compatibility with each other; Ni is infinitely miscible with Co, V with Cr, and Ti with V. Ni-Co also shows good compatibility with Fe, Cr, and V. Fe, Mn, Cr, and V show excellent pairwise compatibility. Moreover, both Co-V(Cr) and Ni-V(Cr) contain low-melting-point compositions. The specific ternary phase diagrams mentioned above are as follows: Figures 4-13 As shown.

[0049] The solidus temperature of the medium-entropy alloy brazing filler metal described in this invention is 1090.2~1099.5℃, and the liquidus temperature is 1103.5~1113.2℃.

[0050] The medium-entropy alloy brazing filler metal provided by this invention employs multiple eutectic compositions such as Ti-Mn-Fe, Ti-Ni-Co, Ti-Co, and Ti-Ni, as well as multiple low-melting-point compositions such as Co-V(Cr), Ni-V(Cr), and Mn-Ni, resulting in a combined melting point reduction. The actual liquidus of the filler metal is 1103.5~1113.2℃, therefore, brazing can be performed within the range of 1180~1190℃. This avoids overheating of the base material due to excessively high brazing temperatures and saves energy. Furthermore, Ni-Co, V-Cr, and Ti-V elements are infinitely miscible, and the elements in Fe-Mn-Cr-V and Fe-Ni-Co-Cr-V exhibit excellent compatibility, preventing the formation of complex brittle phases and resulting in a more uniform distribution of elements in the brazed weld.

[0051] The preparation method of the above-mentioned medium-entropy alloy solder includes the following steps:

[0052] A) Prepare the alloy ingot by mixing the materials according to the mass percentage of the multi-component Ti-based medium-entropy alloy solder and then melting them.

[0053] B) Prepare the alloy ingot into medium-entropy alloy brazing filler metals for different applications.

[0054] In the above preparation method, the raw materials used in the formulation can be selected according to those well known to those skilled in the art, and this application does not impose any special restrictions on them. The melting can be carried out using a melting method well known to those skilled in the art; for example, the melting can be carried out using an electric arc melting method.

[0055] After melting, an alloy ingot is obtained. Depending on the different shapes of the brazing filler metal required for TiAl alloy brazing, the alloy ingot can be further prepared into medium-entropy alloy brazing filler metals of different application forms. Specifically, the shapes of medium-entropy alloy brazing filler metals of different application forms include one or more of the following: molten alloy blocks, molten alloy fragments, molten alloy flakes, molten alloy powder, quenched foil strips, and powder sintered bodies. Molten alloy blocks, molten alloy fragments, molten alloy flakes, and molten alloy powders are all obtained by further processing the alloy ingot to obtain brazing filler metals of different forms. Quenched foil strips are obtained by quenching the alloy ingot to obtain foil strip brazing filler metals. Powder sintered bodies are sintered body brazing filler metals obtained by atomizing, sintering, or other treatments on the alloy ingot. The specific methods for obtaining the above-mentioned brazing filler metals of different shapes can be carried out in accordance with methods known to those skilled in the art, and this application does not impose any special restrictions on this.

[0056] This application also provides the application of the above-mentioned multi-element Ti-based medium-entropy alloy brazing filler metal in brazing connections of Ti-based materials.

[0057] In this application, the multi-component Ti-based medium-entropy alloy brazing filler metal can be used not only for brazing TiAl-based alloys, but also for joining Ti-Al-Nb alloys, Ti-based composites, TiAl-based composites, and other multi-component medium-entropy or high-entropy alloy matrix materials containing only Ti or both Ti and Al.

[0058] This invention also provides a brazing method for TiAl alloys, comprising the following steps:

[0059] S1) Pre-treat the surface of the TiAl alloy base material;

[0060] S2) Add brazing filler metal to the welding position of the base material obtained in step S1) to obtain the assembly;

[0061] S3) Brazing the assembly components;

[0062] The solder is the multi-component Ti-based medium-entropy alloy solder described in the above scheme.

[0063] In the brazing process of TiAl alloy, this application first pre-treats the surface of TiAl alloy base material. Specifically, the pre-treatment removes oil and impurities from the surface of TiAl alloy base material and removes oxides from the position to be welded.

[0064] This application then adds brazing filler metal to the welding positions of the pretreated base material to obtain an assembled component. During this process, different forms of brazing filler metal are placed in different ways. For example, rapidly cooled foil-shaped brazing filler metal can be directly placed between the base materials to be welded. However, for brazing filler metal in the form of molten alloy blocks, molten alloy fragments, molten alloy flakes, molten alloy powder, or sintered powder, a pre-made gap is created between the base materials before adding the brazing filler metal. This pre-made gap is 0.03~0.10mm, more specifically 0.03~0.07mm, and the brazing filler metal is placed through a pre-made bevel. Specifically, as shown... Figure 1 As shown; in this application, the brazing gap between the base materials to be brazed is preferably controlled by machining or tooling fixtures. In this application, two base materials to be brazed, three base materials to be brazed, or four base materials to be brazed can be brazed. That is, there is no particular limitation on the number of base materials in this application, and the brazing filler metal can be placed between two base materials to be brazed.

[0065] Finally, the assembly components are brazed. The brazing is vacuum brazing. Specifically, the brazing process involves placing the assembly components in a vacuum brazing furnace and heating them to 500-700°C at a rate of 10-40°C / min, then heating them to 800-1000°C at a rate of 10-30°C / min, and then heating them to 1180-1190°C at a rate of 10-25°C / min and holding them at that temperature for 20-75 minutes. After the holding period, the components are cooled down at a rate of 10-40°C / min and cooled to room temperature with the furnace.

[0066] More specifically, the assembly is placed in a vacuum brazing furnace and heated to 600°C at a rate of 20-30°C / min, then to 900°C at a rate of 15-25°C / min, and then to 1180-1190°C at a rate of 15-20°C / min and held at that temperature for 30-60 minutes. After the holding period, the assembly is cooled to room temperature at a rate of 20-30°C / min.

[0067] The above vacuum brazing process achieves the brazing of the base material to be welded. See the actual product photo below. Figure 2 As shown:

[0068] This application provides a multi-component Ti-based medium-entropy alloy solder, comprising, by mass percentage: Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 2.0~8.0%, Co: 2.0~8.0%, V: 1.0~7.0%, Cr: 0~6.0%, and Ti: balance. The multi-component Ti-based medium-entropy alloy solder provided in this application has the following advantages:

[0069] 1) The medium-entropy alloy solder significantly reduces the interfacial reaction between the solder and the TiAl base material. Considering the metallurgical effects of the aforementioned elements, the content of the medium-entropy alloy solder was determined as follows: Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 2.0~8.0%, Co: 2.0~8.0%, V: 1.0~7.0%, Cr: 0~6.0%, Ti: balance. Thermodynamic calculations showed that the mixing entropy of the solder was between 10.06 and 11.19 J·mol⁻¹. -1 ·K -1 The solder's properties, falling within the key parameters of a multi-principal alloy (1.0R to 1.5R), indicate that it is a medium-entropy alloy solder. This type of multi-element alloy solder does not undergo a violent chemical reaction with the TiAl base material being soldered, which is beneficial for achieving a good metallurgical bond.

[0070] 2) The liquidus T of the multi-component Ti-based medium-entropy alloy solder of this invention L : 1046.8~1104.5℃, enabling even lower temperature brazing (T b =1180~1190℃); conversely, if the solder liquidus temperature T L Too high, natural brazing temperature T b This will also be higher, making the brazing production process not only excessively energy-intensive and environmentally unfriendly, but also resulting in excessively high T emissions. b It affects the microstructure of the near-joint zone and can also significantly damage the properties of the base material;

[0071] 3) The brazing filler metal of the present invention can be prepared in a wide range of forms: it can be prepared into various forms for use and has various forms of use during brazing; after the medium entropy alloy brazing filler metal is melted, it can be made into corresponding forms for use by different preparation methods, including melted alloy blocks, melted alloy fragments, melted alloy sheets, melted alloy powder, quenched foil strips and powder sintered bodies.

[0072] 4) Advantages in connection performance: Utilizing the design concept of multi-element medium-entropy alloys, more than five alloying elements are added to the brazing filler metal. The solid solution strengthening and grain refinement strengthening effects of different elements are comprehensively utilized to improve the strength of the brazed joint. Brazed joints obtained using the brazing filler metal of this invention under brazing conditions of (1180~1190)℃ / (20-75)min exhibit relatively uniform diffusion of alloying elements in the brazed joint, achieving element content levels of 0.5%≤Fe≤4.0%, 0.5%≤Mn≤4.0%, 0.25%≤Ni≤2.0%, 0.25%≤Co≤2.0%, 1.0%≤Cr≤6.0%, and 0.5%≤V≤3.0% (at.%), thus playing a role in small or trace strengthening by alloying elements. The microstructure of brazed joints obtained using the brazing filler metal of this invention is mainly γ-TiAl and α2-Ti3Al, such as... Figure 3 As shown;

[0073] Brazed joints obtained using the brazing filler metal of this invention at (1180~1190)℃ / (20-75)min exhibit a room temperature tensile strength of 479~508 MPa and a joint strength coefficient of 0.81~0.86; the high-temperature tensile strength reaches 493~509 MPa at 650℃, 514~524 MPa at 700℃, 495~521 MPa at 750℃, 488~499 MPa at 800℃, and 396~418 MPa at 850℃. Within this wide temperature range of 700~850℃, the high-temperature strength coefficient of the joint remains consistently above 0.85. The average high-temperature tensile strength of the brazed joints in the embodiments of this application at 650~850℃ is as follows: Figure 14 As shown, by Figure 14 It is known that the high-temperature strength of this application in the wide temperature range of 650~850℃ is significantly better than that of Ti-Fe-Mn brazing filler metal or Ti-Zr-Cu-Ni brazing filler metal, wherein the Ti-Fe-Mn brazing filler metal is specifically Ti-22Fe-23Mn (wt%) brazing filler metal, and the Ti-Zr-Cu-Ni brazing filler metal is specifically Ti-37.5Zr-15Cu-15Ni (wt%) brazing filler metal. Furthermore, the TiAl / TiAl brazed joint obtained by the brazing filler metal of this invention has significantly better high-temperature strength in the wide temperature range of 650~850℃ than the high-temperature strength of brazed joints corresponding to simple ternary and quaternary brazing filler metal alloys such as Ti-Ni-Nb or Ti-Zr-Ni-Nb.

[0074] 5) The brazing filler metal of this invention does not contain precious metals: Ti, Fe, Mn, Ni, Co, Cr, and V are all conventional metallic elements and do not contain precious metals, so it has a great price advantage in terms of economy;

[0075] 6) The brazing filler metal of the present invention is not only applicable to brazing of materials such as TiAl alloy, but also to the joining of Ti-Al-Nb alloy, Ti-based composite material, TiAl-based composite material, and other multi-element medium-entropy or high-entropy alloy matrix materials containing one element Ti or two elements Ti and Al.

[0076] To further understand the present invention, the following detailed description of the multi-element medium-entropy alloy brazing filler metal and the brazing method of TiAl alloy provided by the present invention is provided in conjunction with the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0077] Examples 1-2

[0078] This document outlines the application method for a Ti-Mn-Fe-Ni-Co-V hexa-element medium-entropy alloy solder. The solder composition by mass percentage is as follows: Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 2.0~8.0%, Co: 2.0~8.0%, V: 1.0~7.0%, Cr: 0%, Ti: balance; the liquidus temperature of the solder is between 1103.5~1113.2℃.

[0079] The chemical composition of the solder in Examples 1 and 2 is shown in Table 1 (by mass percentage).

[0080] Table 1. Chemical composition data of the medium-entropy alloy brazing filler metal provided in this embodiment.

[0081]

[0082] The brazing of TiAl alloys using the chemical composition of the brazing filler metals in Examples 1-2 of Table 1 includes the following steps:

[0083] (1) After preparing the alloy ingots according to the chemical composition of the brazing filler metal in Table 1, the alloy ingots are melted by electric arc melting and then prepared into powder sintered bodies, blocks, powders or quenched strips.

[0084] (2) The base material is a TiAl-based alloy with a nominal composition of Ti-46Al-(3~4)Nb-(2~3)(Cr,Ta,B)(at.%). Pure Ti foil strips with a thickness of 0.03~0.07 mm are cut into narrow strips with a width of 0.5~1 mm and spot-welded to one side of the base material to be welded using a spot welding machine. Then, the base materials on both sides are clamped with tooling to control the brazing gap to 0.03~0.07 mm. Then, the brazing filler metal is prefabricated at the position to be welded on the base material according to the morphology in Table 2 to form an assembly component.

[0085] (3) Place the assembled components into a vacuum furnace, with a vacuum level of 5.0 × 10⁻⁶. -3Pa, the brazing temperature is 1185℃; specifically: heat up at a rate of 10~40℃ / min to 600℃, then heat up at a rate of 10~30℃ / min to 900℃, then heat up at a rate of 10~25℃ / min to 1185℃ and hold for 45 or 60 min; after holding, cool down at a rate of 10~40℃ / min and cool to room temperature with the furnace.

[0086] The performance of the brazed joints corresponding to Examples 1 and 2 is shown in Table 2;

[0087] Table 2 Performance data of brazed joints obtained in Examples 1-2

[0088]

[0089] Examples 3-4

[0090] This document outlines the application of a seven-element medium-entropy alloy brazing filler metal (Ti-Mn-Fe-Ni-Co-V-Cr). The filler metal composition by mass percentage includes: Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 2.0~8.0%, Co: 2.0~8.0%, V: 1.0~7.0%, Cr: 0~6.0%, Ti: balance; the liquidus temperature of the filler metal is between 1103.5~1113.2℃.

[0091] The chemical composition of the solder in Examples 3-4 is shown in Table 3 (by mass percentage).

[0092] Table 3 Chemical composition data of the medium-entropy alloy brazing filler metal provided in this embodiment

[0093]

[0094] The brazing of TiAl alloys using the chemical composition of the brazing filler metals in Examples 3-4 of Table 3 includes the following steps:

[0095] (1) After preparing the alloy ingots according to the chemical composition of the brazing filler metal in Table 3, the alloy ingots are melted into powder, powder sintered body, block or quenched strip.

[0096] (2) The base material is a TiAl-based alloy with a nominal composition of Ti-46Al-(3~4)Nb-(2~3)(Cr, Ta, B) (at.%). Pure Ti foil strips with a thickness of 0.03~0.07 mm are cut into narrow strips with a width of 0.5~1 mm and spot-welded to one side of the base material to be welded using a spot welding machine. The base materials on both sides are then clamped with tooling to control the brazing gap to 0.03~0.07 mm. Then, the brazing filler metal is prefabricated at the position to be welded on the base material according to the different morphological combinations in Table 4 to form an assembly component.

[0097] (3) Place the assembled components into a vacuum furnace, with a vacuum level of 5.0 × 10⁻⁶. -3 Pa, select a brazing temperature of 1185℃; specifically: heat up to 600℃ at a rate of 10~40℃ / min, then heat up to 900℃ at a rate of 10~30℃ / min, then heat up to 1185℃ at a rate of 10~25℃ / min and hold for 30 or 45 min; after holding, cool down at a rate of 10~40℃ / min and cool to room temperature with the furnace.

[0098] The performance of the brazed joints corresponding to Examples 3 and 4 is shown in Table 4;

[0099] Table 4 Performance data of brazed joints obtained in Examples 3-4

[0100]

[0101] The brazing filler metal of this invention is not only applicable to brazing of materials such as TiAl alloys, but also to the joining of Ti-Al-Nb alloys, Ti-based composite materials, TiAl-based composite materials, and other multi-element medium-entropy or high-entropy alloy matrix materials containing only Ti or both Ti and Al.

[0102] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0103] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-component Ti-based medium-entropy alloy solder, characterized in that, By weight percentage, including: Mn: 16.0~22.0%, Fe: 12.0~18.0%, Ni: 3.2~8.0%, Co: 5.6~8.0%, V: 1.0~7.0%, Cr: 0~6.0%, Ti: balance; The addition of the above-mentioned metal elements to the solder can form a variety of eutectic compositions such as Ti-Mn-Fe, Ti-Ni-Co, Ti-Co and Ti-Ni, as well as a variety of low-melting-point compositions such as Co-V, Co-Cr, Ni-V, Ni-Cr and Mn-Ni, which can reduce the melting point. The actual liquidus of the solder is 1103.5~1113.2℃. On an atomic percentage basis, the alloying elements in the brazed joint reach the levels of 0.5%≤Fe≤4.0%, 0.5%≤Mn≤4.0%, 0.25%≤Ni≤2.0%, 0.25%≤Co≤2.0%, 1.0%≤Cr≤6.0%, and 0.5%≤V≤3.0%; the microstructure of the brazed joint is mainly γ-TiAl and α2-Ti3Al.

2. The multi-component Ti-based medium-entropy alloy solder according to claim 1, characterized in that, The preparation method of the medium-entropy alloy solder includes the following steps: A) Prepare the alloy ingot by mixing the materials according to the mass percentage of the multi-component Ti-based medium-entropy alloy solder and then melting them. B) Prepare the alloy ingot into medium-entropy alloy brazing filler metals for different applications.

3. The multi-component Ti-based medium-entropy alloy solder according to claim 1 or 2, characterized in that, The application forms of the multi-element Ti-based medium-entropy alloy solder include one or more of the following shapes: molten alloy block, molten alloy granules, molten alloy sheet, molten alloy powder, and rapidly cooled foil strip.

4. The application of the multi-component Ti-based medium-entropy alloy brazing filler metal according to any one of claims 1 to 3 in brazing connections of Ti-based materials.

5. A brazing method for TiAl alloy, comprising the following steps: S1) Pre-treat the surface of the base material; S2) Add brazing filler metal to the welding position of the base material obtained in step S1) to obtain the assembly; S3) Brazing the assembly components; The brazing filler metal is the multi-component Ti-based medium-entropy alloy brazing filler metal as described in any one of claims 1 to 3.

6. The brazing method according to claim 5, characterized in that, The brazing gap between the base materials in the assembly is 0.03~0.10mm.

7. The brazing method according to claim 5, characterized in that, The brazing temperature is 1180~1190℃.

8. The brazing method according to claim 5, characterized in that, The brazing method is vacuum brazing.

9. The brazing method according to claim 5 or 8, characterized in that, The brazing specifically refers to: The assembly is placed in a vacuum brazing furnace and heated to 500-700°C at a rate of 10-40°C / min, then to 800-1000°C at a rate of 10-30°C / min, and then to 1180-1190°C at a rate of 10-25°C / min and held for 20-75 minutes. After the holding period, the assembly is cooled to room temperature at a rate of 10-40°C / min.

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