Six-element medium-entropy alloy brazing filler metal and preparation method therefor, and braze welding method

Abstract

The present invention relates to the technical field of braze welding, and provides a Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy brazing filler metal used for the braze welding of pure titanium and a titanium alloy, and a use method. The Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy brazing filler metal provided in the present invention comprises the following components in percentages by weight: 9.5-13.9% of Ti, 5.5-9.5% of Ni, 5.0-9.5% of Cu, 2.0-8.5% of Co, 0.0-2.0% of Hf, and the balance of Zr. The present invention has the following technical effects: the liquidus temperature of the brazing filler metal is between 769°C-782°C, the brazing filler metal is easily formed into an amorphous brazing filler metal alloy, and the shear strength of a pure titanium-titanium alloy joint obtained after heat preservation is performed for 10 minutes at a braze-welding temperature of 810°C-828°C reaches 243-280 MPa.

Description

A six-element medium-entropy alloy solder and its preparation method and brazing method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 27, 2023, with application number 2023118257442 and invention name “A six-element medium-entropy alloy solder, its preparation method and brazing method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The invention belongs to the technical field of brazing, and in particular relates to a six-element medium-entropy alloy brazing filler metal, a preparation method thereof, and a brazing method. Background Art

[0003] Titanium and its alloys have high specific strength and excellent corrosion resistance. They are one of the main structural materials of modern aircraft and engines. They can reduce the weight of aircraft or engines and improve structural efficiency. For the brazing connection of titanium alloys, Ti-based (Ti element accounts for more than 40% by weight) or TiZr-based (Ti element accounts for more than 35% and Zr element accounts for more than 20% by weight) brazing filler metals are usually selected as brazing materials to obtain better joint structure and corresponding higher joint strength and better corrosion resistance.

[0004] However, the phase transition temperature of pure titanium is T β The phase transition temperature of TC16 (Ti-3Al-5Mo-4.5V, weight percentage) and TC18 (Ti-5Al-5Mo-5V-1Cr-1Fe, weight percentage) titanium alloys is even as low as 840°C to 880°C, that is, the brazing temperature corresponding to the brazing connection is required to be lower than 840°C, and in order to ensure that the titanium alloy base material being brazed does not undergo phase transformation during the brazing process, the safer brazing temperature should not be higher than 830°C. In this way, considering that brazing is generally carried out at a temperature 30°C to 50°C higher than the melting temperature of the brazing filler metal, the liquidus temperature of the ideal brazing filler metal required for the connection of pure titanium materials and the above-mentioned titanium alloys including TC6 and TC18 is preferably lower than 790°C. In addition, it is very important that for the brazing connection of pure titanium and titanium alloys, whether it is aircraft ducts or thin-walled complex structures of aviation and marine heat exchangers and other various engineering application requirements, the brazing joints pursue both high strength and good plasticity to ensure the safety and service life of the welded structure.

[0005] However, the liquidus temperature of Ti-based or TiZr-based solders is relatively high. For example, the typical Ti-15Cu-15Ni alloy (weight percentage) has a high liquidus temperature and is only suitable for brazing β phase transformation temperature T βTitanium alloys with temperatures above 960°C; Ti-13Zr-21Cu-9Ni alloy (weight percentage), whose liquidus temperature is still relatively high, can only be brazed at a brazing temperature of 920°C-940°C for titanium alloys; and some brazing materials can be used for brazing pure titanium and titanium alloys at a brazing temperature of around 880°C, but the strength of the brazed joint is difficult to exceed 500MPa, and the brazed joint still shows obvious brittleness. Generally, after solving the basic weldability of a certain base material to be welded, the melting temperature of the brazing material is further reduced to further reduce the required brazing temperature, and also to improve the joint strength, while also reducing the brittleness of the brazed joint. Improving or improving in these three aspects at the same time is a very challenging technical difficulty. At present, there is still a lack of brazing materials that can be used for brazing pure titanium or pure titanium and titanium alloys at temperatures below 872°C, and that make the brazed joint have both high strength and plasticity. At the same time, under the premise of meeting the mechanical properties of the brazed joint, reducing the brazing temperature as much as possible to save energy has been a goal pursued in the field of pure titanium and titanium alloy brazing. However, there is currently a clear lack of brazing materials that can braze pure titanium and titanium alloys at temperatures below 830°C and make the brazed joints have higher strength. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a Zr-Ti-Hf-Ni-Cu-Co hexa-element medium-entropy alloy brazing material. The brazing material provided by the present invention has a liquidus temperature between 769°C and 782°C, and can be used to braze pure titanium or pure titanium and titanium alloy at a temperature of 815°C to 828°C, and the obtained brazed joint has high strength.

[0007] The present invention provides a Zr-Ti-Hf-Ni-Cu-Co hexa-element medium-entropy alloy solder, wherein the weight percentages of the solder components are as follows:

[0008] Ti: 9.5~13.9; Ni: 5.5~9.5; Cu: 5.0~9.5; Co: 2.0~8.5; Hf: 0.0~2.0; Zr: balance

[0009] Preferably, the weight percentage of the solder composition is:

[0010] Ti: 9.5~13.0; Ni: 5.5~9.0; Cu: 5.0~9.5; Co: 3.0~8.0; Hf: 0.0~2.0; Zr: balance

[0011] Preferably, the liquidus temperature of the solder is 769°C to 782°C;

[0012] The solder is a medium-entropy alloy solder in one or more of the following shapes: amorphous foil, powder, alloy block or powder sintered body.

[0013] The present invention provides a method for preparing a Zr-Ti-Hf-Ni-Cu-Co hexa-element medium-entropy alloy solder, comprising:

[0014] A) smelting metal raw materials to prepare alloy ingots;

[0015] B) preparing the alloy ingot to obtain a medium-entropy alloy solder; the medium-entropy alloy solder has a shape including an amorphous foil strip, a powder, an alloy block, and a powder sintered body.

[0016] Preferably, step B) specifically includes one or more of the following steps:

[0017] i) preparing the alloy ingot into alloy powdered brazing material by an argon atomization powder making method or a plasma rotating electrode atomization method;

[0018] ii) preparing the alloy ingot into an amorphous alloy foil solder by a single-roller rapid quenching method;

[0019] iii) mechanically crushing the alloy ingot to obtain a solder alloy block;

[0020] iv) Firstly, a powdered solder is prepared according to the above method, and then pressed and sintered to obtain a solder sintered body.

[0021] The present invention provides use of any one of the above-mentioned Zr-Ti-Hf-Ni-Cu-Co hexameric medium-entropy alloy brazing filler metals in brazing pure titanium and / or titanium alloys.

[0022] The present invention provides a brazing method for pure titanium and / or titanium alloy, comprising the following steps:

[0023] a) Material preparation: Prepare the base material of pure titanium and / or titanium alloy to be welded, and obtain the pretreated base material after pretreatment such as specimen processing and surface cleaning;

[0024] b) adding a solder to the surface of the pretreated base metal to be welded to obtain an assembled component; the solder is the solder described in the above technical solution or the solder prepared by the preparation method described in the above technical solution;

[0025] c) Brazing the assembled components.

[0026] Preferably,

[0027] The pretreatment in step a) is specifically to remove oxides, oils or surface contaminants on the surface of the parent material;

[0028] The step b) further comprises controlling the brazing gap between the substrates to be brazed to be 0.01-0.08 mm by means of a fixture.

[0029] Preferably, the brazing temperature in step c) is:

[0030] When the substrate contains pure titanium, the brazing temperature T b Temperature: 810℃~860℃;

[0031] When the substrate to be welded is TC16 or TC18 titanium alloy, the brazing temperature T b Can be: 810℃~828℃;

[0032] When the matrix is ​​a titanium alloy with a phase transition temperature higher than 840°C, the brazing temperature T b The temperature can be 810°C to 828°C, or 10°C lower than the phase transformation temperature of the titanium alloy base material to be welded.

[0033] Preferably, the brazing method in step c) is vacuum brazing or induction heating brazing;

[0034] The vacuum brazing parameters are as follows: the vacuum degree in the furnace is not less than 1×10 -3 Pa, heating at a rate of 20-40℃ / min to 500℃; continuing heating at a rate of 15-25℃ / min to T b Keep warm for 10 to 25 minutes; then cool down at a rate of 15 to 25°C / min and cool to room temperature along with the furnace.

[0035] The induction heating brazing parameters are as follows: the vacuum degree is less than 2×10 -1 Fill the chamber with inert gas to 70-100 kPa, then heat it to T at a heating rate of 50-100 °C / min under inert gas conditions. b , keep warm for 1min to 10min, then stop induction heating and cool naturally to room temperature.

[0036] Compared to the prior art, the present invention provides a Zr-Ti-Hf-Ni-Cu-Co 6-element medium-entropy alloy brazing filler metal. The filler metal's composition by weight is as follows: Ti: 9.5-13.9; Ni: 5.5-9.5; Cu: 5.0-9.5; Co: 2.0-8.5; Hf: 0.0-2.0; and Zr: the balance. The present invention offers the following technical advantages: the filler metal's liquidus temperature ranges from 769°C to 782°C, making it easy to form an amorphous filler metal alloy. The shear strength of a pure titanium-titanium alloy joint achieved at a brazing temperature of 810°C to 828°C for 10 minutes reaches 243-280 MPa.

[0037] The advantages and beneficial effects of the solder of the present invention are as follows:

[0038] (1) Characteristics and advantages of the element composition of the solder alloy: Utilizing the principle of diversified alloy design, this invention patent has designed a total of 6 constituent elements, of which Zr, Ti, and Hf are 3 elements that can infinitely dissolve in each other, and there is no tendency for brittle intermetallic compounds to form between them. At the same time, Ni, Cu, and Co are added to the solder alloy as melting-reducing elements, respectively. They achieve the effect of lowering the melting point of the solder alloy through the principles of ternary low-melting eutectics such as Cu-Ni-Zr, Cu-Ni-Ti, and Cu-Ti-Zr, as well as binary low-melting eutectics such as Co-Ti and Co-Zr, as shown in Figures 1 to 5. Moreover, after thermodynamic calculations, the mixing entropy ΔS of the six-element solder alloy of the present invention is mix (J.K -1 mol -1 ) values ​​are between 9.72 and 11.32, satisfying the thermodynamic conditions of high entropy alloys ΔS mix The value falls within the range of 1.0R-1.5R, which is determined to be a medium-entropy alloy brazing filler metal. Therefore, it can play a good strengthening and toughening role in the brazing joints of pure titanium and the combination of pure titanium and titanium alloy.

[0039] (2) The melting temperature of the solder alloy is effectively reduced, which can meet the ideal requirement of a brazing temperature not exceeding 830°C. In the Zr-Ti-Hf-Ni-Cu-Co hexa-element solder alloy applied, Ni, Cu, and Co are used to reduce the melting point. The melting point reduction effect is much better than that of single Cu, Ni, and Co or any two of them. The actual liquidus temperature of the solder is between 769°C and 782°C, as shown in Figure 6. Therefore, brazing can be carried out within the temperature range of 810-828°C, which not only avoids damage to the performance of the parent material being welded due to excessively high brazing temperature, but also helps to save energy during the brazing process. In this regard, for large gap joints (such as 0.3mm to 3mm), when brazing is performed by adding titanium alloy powder and solder alloy powder at the same time, it takes a long time (such as more than 1 hour) for diffusion sintering to densify the brazed joint. The energy saving effect of the brazing process corresponding to this low brazing temperature is more obvious.

[0040] (3) Since the liquidus temperature of the solder of the present invention is lower than 782°C, it is particularly suitable for brazing TC16 and TC18 titanium alloys with a phase transition temperature of 840°C to 880°C. In addition, it is also suitable for brazing pure titanium-titanium alloy combined joints, and can be used for brazing conventional titanium alloys such as TC4. It is applicable to a wide range of titanium alloy base materials to be welded, and the brazing temperature can be selected in a wide range. For example, for TA2 pure titanium, the brazing temperature can be in the range of 810°C to 870°C, and for TC4 titanium alloy (whose phase transition temperature is about 970°C), the brazing temperature can be in the range of 830°C to 910°C.

[0041] (4) The composition design of the brazing alloy of the present invention fully considers the need for it to have good amorphous foil forming ability. In particular, for the brazing connection of a multi-layer thin-walled heat exchanger with a complex structure composed of pure titanium fins and titanium alloy partitions, the use of complete and continuous amorphous alloy foil between layers for pre-welding filling and assembly can ensure convenient and efficient assembly and stable and controllable brazing quality. Among the six constituent elements of the solder alloy invented in the present application, one category is Zr, Ti, and Hf elements, and the other category is Ni, Cu, and Co elements. Each category is similar elements, but the two categories of elements are different elements when crossed, as shown in Figure 7. Through the appropriate addition amounts of each of them, they are jointly melted down. This design concept fully utilizes the design principles of amorphous alloys such as "eutectic point criterion, atomic size differentiation, and coexistence of similar and different elements". Therefore, under the premise of ensuring a sufficiently low melting temperature, the solder of the present invention has amorphous foil forming ability that is significantly better than that of the Zr-Ti-Ni system and ZrTiNiNb (Hf) solder. Using a single-roller rapid quenching method, amorphous solder foil with a width of 25-50 mm and a thickness of 25-60 μm can be stably obtained. The solder foils produced in different batches all show amorphous characteristics, as shown in Figure 8. At the same time, because the solder of the present invention has strong amorphous foil forming ability, the yield rate of preparing solder foil is increased to more than 1.5 times that of Zr-Ti-Ni system solder and Zr-Ti-Ni-Nb (Hf) solder.

[0042] (5) Using the brazing filler metal of the present invention, corresponding to the pure titanium-titanium alloy combined joint, for example, under the brazing conditions of 825℃-10min, the microstructure of the pure titanium-pure titanium and pure titanium-titanium alloy brazed joints is shown in FIG9. The width of the central area of ​​the joint is about 30μm, and there is a diffusion reaction zone of about 25-40μm between the central area of ​​the joint and the pure titanium-titanium alloy base material to be welded. However, there is no obvious white bright color Cu-Ti, Cu-Zr, Ni-Ti, Ni-Zr, Co-Ti or Co-Zr intermetallic compounds in the entire brazed joint. The brazing filler metal of the present invention adopts a combined melting reduction method with balanced content of the three elements Ni, Cu and Co, which effectively avoids the tendency of forming strong brittle intermetallic compounds in the brazed joint due to excessive addition of one element when the melting reduction is only relied on. When the brazing is kept warm for a sufficient time, the Ni, Cu and Co elements exist in the (Zr, Ti, Hf) solid solution in the form of solid solution. They themselves do not cause joint brittleness, but instead play an important role in strengthening the brazed joint. Therefore, by using the brazing filler metal of the present invention, a brazed joint obtained under appropriate brazing process conditions has both good strength and plasticity.

[0043] (6) The solder of the present invention has a strong ability to wet, spread and fill gaps on pure titanium and titanium alloy substrates during brazing. For example, under vacuum heating conditions of 825°C for 10 minutes, the solder exhibits good wettability on pure titanium TA2, with a wetting angle of only 37°, as shown in Figure 10; under vacuum brazing conditions of 860°C for 10 minutes, the filling length of the solder on titanium alloy TA18 reaches 75-90 mm, as shown in Figure 11.

[0044] (7) The brazing filler metal of the present invention achieves a comprehensive effect of high strength and good plasticity for brazing pure titanium or a combination of pure titanium and titanium alloys at a brazing temperature of 850-865°C and a holding time of 18-25 minutes: the tensile strength of TA2-TC4 and TA2-TA18 brazed joints at room temperature is above 530 MPa, while the elongation of the two joints reaches above 10% and 12%, respectively. This fundamentally eliminates the brittle characteristics of brazed joints corresponding to traditional brazing fillers and achieves a strong-plasticity match between the joints. At the same time, the shear strength of TA2-TA18, TA2-TC16, and TA2-TC18 joints obtained by brazing at 810-828°C reaches 243 MPa-280 MPa at room temperature.

[0045] (8) As previously mentioned, the brazing filler metal of the present invention does not contain the high-melting-point element Nb, and explicitly requires that the Hf content be controlled to no more than 2.0% by weight. Furthermore, the addition amounts of the three melting-reducing elements, Ni, Cu, and Co, are relatively balanced. These factors are all conducive to obtaining a uniformly composed ingot through smelting. Furthermore, through the uniformly composed ingot, a uniform, segregation-free amorphous alloy foil brazing filler metal can be easily obtained through the single-roll rapid quenching method. Furthermore, through the uniformly composed ingot, the powdering process has been verified to be safe and stable by both argon atomization and plasma rotating electrode atomization methods, and a uniformly composed powdered brazing filler metal can be obtained.

[0046] (9) The brazing alloy itself has the characteristics of high alloying. During the brazing process, the Cu, Ni, and Co elements diffuse into the pure titanium or titanium alloy matrix to be welded, and the Ti element in the pure titanium or titanium alloy matrix to be welded diffuses into the brazing seam area. Therefore, the brazed joint appears to be a TiZr (Hf)-based super solid solution, in which the content of Cu, Ni, and Co elements is at a relatively low level. Therefore, the brazed joint not only has good mechanical properties, but also the high alloying characteristics of the brazed joint ensure that it has good corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Cu-Ni-Zr ternary phase diagram;

[0048] Figure 2 Cu-Ni-Ti ternary phase diagram;

[0049] Figure 3 Cu-Co-Zr ternary phase diagram;

[0050] Fig. 4 Co-Ti binary phase diagram;

[0051] Fig. 5 Co-Zr binary phase diagram;

[0052] Two typical solidus and liquidus temperatures of entropy alloy solder in Figure 6;

[0053] Figure 7 is a schematic diagram showing the positions of the constituent elements of the entropy alloy solder in the periodic table;

[0054] Figure 8 Typical XRD pattern of amorphous solder foil;

[0055] Figure 9: Microstructure of pure titanium TA2-titanium alloy TA18 brazed joint (825℃-10min brazing);

[0056] Figure 10: Wetting cross section of solder on pure titanium TA2 under vacuum heating conditions at 825°C for 10 min.

[0057] In Figure 11, the entropy alloy filler metal ... DETAILED DESCRIPTION

[0058] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0059] In this application, the term "and / or" describes the association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0060] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0061] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0062] The present invention provides a Zr-Ti-Hf-Ni-Cu-Co hexa-element medium-entropy alloy solder, wherein the weight percentages of the solder components are as follows:

[0063] Ti: 9.5~13.9; Ni: 5.5~9.5; Cu: 5.0~9.5; Co: 2.0~8.5; Hf: 0.0~2.0; Zr: balance

[0064] According to the present invention, the preferred weight percentages of the solder components are:

[0065] Ti: 9.5~13.0; Ni: 5.5~9.0; Cu: 5.0~9.5; Co: 3.0~8.0; Hf: 0.0~2.0; Zr: balance

[0066] The liquidus temperature of the solder of the present invention is 769° C. to 782° C.

[0067] The present invention has found that the combined melting reduction of Ni, Cu and Co elements has a much better melting reduction effect than that of single Cu, Ni, Co or any two of them together. The actual liquidus temperature of the solder is between 769°C and 782°C, which is applicable to a wide range of titanium alloy base materials to be welded, and the range of selectable brazing temperatures is also wide.

[0068] In some embodiments, titanium-containing materials may include, but are not limited to: ribbed wall structures of pure titanium and / or titanium alloys; thin-walled structures of pure titanium and / or titanium alloys; sandwich structures of pure titanium and / or titanium alloys; and any titanium alloy-titanium alloy structure. The brazing filler metal may be a medium-entropy alloy brazing filler metal in one or more of the following forms: amorphous foil, powder, alloy block, or powder sintered body.

[0069] This invention patent has designed a total of 6 constituent elements, among which Zr, Ti, and Hf are three elements that can be infinitely soluble in each other, and there is no tendency for brittle intermetallic compounds to form between them. At the same time, Ni, Cu, and Co are added to the solder alloy as melting point reducing elements. They achieve the effect of lowering the melting point of the solder alloy through the principles of ternary low-melting eutectics such as Cu-Ni-Zr, Cu-Ni-Ti, and Cu-Ti-Zr, as well as binary low-melting eutectics such as Co-Ti and Co-Zr. Moreover, after thermodynamic calculations, the mixing entropy ΔS of the six-element solder alloy of the present invention is mix (J.K -1 mol -1 ) values ​​are between 9.72 and 11.32, satisfying the thermodynamic conditions of high entropy alloys ΔS mixThe value falls within the range of 1.0R-1.5R, which is determined to be a medium-entropy alloy brazing filler metal. Therefore, it can play a good strengthening and toughening role in the brazing joints of pure titanium and the combination of pure titanium and titanium alloy.

[0070] The present invention provides a method for preparing a Zr-Ti-Hf-Ni-Cu-Co hexa-element medium-entropy alloy solder, comprising:

[0071] A) smelting metal raw materials to prepare alloy ingots;

[0072] B) preparing the alloy ingot to obtain a medium-entropy alloy solder; the medium-entropy alloy solder has a shape including an amorphous foil strip, a powder, an alloy block, and a powder sintered body.

[0073] The present invention firstly smelts metal raw materials to prepare alloy ingots.

[0074] Use high-purity Zr, Ti, Ni, Cu, Co, and Hf elements with a purity of 99.5%-99.9% and weigh them according to the weight ratio; or use high-purity Zr containing 1%-2.5% Hf element, and add Hf element to the raw materials required for the solder through high-purity Zr containing a certain amount of Hf element, and then add pure Hf separately according to the insufficient Hf content in the required composition, while the purity of other elements remains unchanged.

[0075] The present invention preferably adopts arc melting method to melt the raw materials into alloy ingots under inert gas protection conditions. The recommended parameters of arc melting are: the melting chamber is vacuumed to 2×10 -1 After Pa, fill with argon to standard atmospheric pressure, arc striking current 80A, stable melting current 200A, melting time 13 to 25s. To ensure uniform alloy composition, it is recommended to melt 2 to 4 times.

[0076] The alloy ingot is prepared to obtain a medium-entropy alloy solder.

[0077] In some embodiments of the present invention, one or more of the following steps are specifically included:

[0078] i) preparing the alloy ingot into an alloy powdered solder by an argon atomization powdering method or a plasma rotating electrode atomization method; the parameters of the argon atomization powdering method of the present invention specifically include: in an inert gas protection state of argon or helium, using a clamp to clamp the rod and place it in a conical induction coil; the conical induction coil has a height of 500-700 mm, a lower end diameter of 40-65 mm, and a cone angle of 40-65°; the power of the power supply equipment providing current to the induction coil is 10-23 kW and the frequency is 3500 Hz; the rod feed speed is 2.0-4.5 mm / s; and the atomization pressure is 2.0-6.5 MPa.

[0079] The parameters of the plasma rotating electrode atomization method of the present invention specifically include: the diameter of the solder master alloy rod is 30-60 mm, the rotation speed is 20000-35000 r / min, and the feeding speed is 2-5 mm / min.

[0080] ii) Using a single-roller rapid quenching method to prepare the alloy ingot into an amorphous alloy foil solder. The parameters of the single-roller rapid quenching method of the present invention specifically include: in an inert gas protection state of argon or helium, a quartz crucible is used to place the rods therein, and the quartz tube crucible is placed in a ring-shaped induction coil; the induction coil height is 300-600 mm, and the lower end tube width is 30-50 mm°; the rod feed speed is 0.2-0.5 m / s; the single roller speed is 1300-1800 r / min; and the injection pressure is 50-70 kPa.

[0081] iii) mechanically crushing the alloy ingot to obtain a solder alloy block;

[0082] The parameters of the mechanical crushing of the present invention specifically include: manually hitting the solder master alloy with a hammer weighing 10kg to 30kg until it is crushed, or using a processing method such as wire cutting to crush the master alloy.

[0083] iv) Firstly, a powdered solder is prepared according to the above method, and then pressed and sintered to obtain a solder sintered body.

[0084] The pressing and sintering process of the present invention specifically includes: the solder powder particle size is -150 mesh, the pressing pressure is 60-80 kN, and the sintering specification in the vacuum furnace is: the vacuum degree is 8×10 -3 Pa, temperature 730~750℃, holding time 20~40min.

[0085] The present invention provides use of any one of the above-mentioned Zr-Ti-Hf-Ni-Cu-Co hexameric medium-entropy alloy brazing filler metals in brazing pure titanium and / or titanium alloys.

[0086] The above-mentioned Zr-Ti-Hf-Ni-Cu-Co hexa-element medium-entropy alloy brazing filler metal of the present invention can be used not only for brazing between pure titanium and pure titanium, brazing between pure titanium and titanium alloys, but also for brazing between titanium alloys and titanium alloys, and good results can be achieved.

[0087] The present invention provides a brazing method for pure titanium and / or titanium alloy, comprising the following steps:

[0088] a) Material preparation: prepare the base material of pure titanium and / or titanium alloy to be welded, and obtain the pretreated base material after pretreatment;

[0089] b) adding solder to the surface to be welded of the pretreated base metal to obtain an assembled component;

[0090] c) Brazing the assembled components.

[0091] The above-mentioned pure titanium and / or titanium alloy of the present invention includes pure titanium-pure titanium, pure titanium-titanium alloy, and titanium alloy-titanium alloy.

[0092] The brazing method of pure titanium / or titanium alloy provided by the present invention first includes material preparation.

[0093] The base material of pure titanium and / or titanium alloy to be welded is prepared and pretreated to obtain a pretreated base material; the pretreatment specifically removes oxides, oils or surface contaminants on the surface of the base material; the present invention does not limit the specific removal method, which is well known to those skilled in the art.

[0094] A solder is added to the surface to be welded of the pretreated base material to obtain an assembled component; the solder is the solder described in the above technical solution or the solder prepared by the preparation method described in the above technical solution.

[0095] Preferably, the method further includes controlling the brazing gap between the substrates to be brazed to be 0.01 to 0.08 mm by a fixture.

[0096] The present invention does not limit how the fixture controls the brazing gap, which is well known to those skilled in the art.

[0097] The assembled components are brazed to obtain the product.

[0098] Place the assembled components into a vacuum brazing furnace with a vacuum degree of no less than 1×10 -3 Pa.

[0099] Select the brazing temperature according to the phase change temperature of the base material.

[0100] In some embodiments of the present invention, the brazing temperature is specifically:

[0101] When the substrate contains pure titanium, the brazing temperature T b Temperature: 810℃~860℃;

[0102] When the matrix is ​​entirely titanium alloy, T b The phase transition temperature of the present invention is not higher than the phase transition temperature of the corresponding titanium alloy.

[0103] When the substrate to be welded is TC16 or TC18 titanium alloy, the brazing temperature T b Temperature: 810℃~828℃;

[0104] When the matrix is ​​TA18 or TA2 titanium alloy with a phase transition temperature higher than 840°C, the brazing temperature T bSet to: 810℃~830℃, and can also be set to 810℃~860℃. When the substrate is TC4 titanium alloy, the brazing temperature T b Can be set to: 810℃~890℃.

[0105] The brazing method of the present invention is vacuum brazing or induction heating brazing;

[0106] In some embodiments of the present invention, the vacuum brazing parameters are as follows: the vacuum degree in the furnace is not less than 1×10 -3 Pa, heating at a rate of 20-40℃ / min to 500℃; continuing heating at a rate of 15-25℃ / min to T b Keep warm for 10 to 30 minutes; then cool down at a rate of 15 to 25°C / min and cool to room temperature along with the furnace.

[0107] In some embodiments of the present invention, the induction heating brazing parameters are as follows: heating to T at a heating rate of 50°C / min to 100°C / min under inert gas conditions. b , keep warm for 1min to 10min, then stop induction heating and cool naturally to room temperature.

[0108] The brazing filler metal of the present invention utilizes a combined melting reduction method with balanced content of Ni, Cu, and Co. This effectively avoids the tendency of excessive addition of a single element to cause the formation of strong brittle intermetallic compounds in the brazed joint. Using the brazing filler metal of the present invention, brazed joints produced under appropriate brazing process conditions exhibit both excellent strength and ductility. The filler metal of the present invention exhibits excellent wetting, spreading, and gap-filling capabilities on pure titanium and titanium alloy substrates during brazing.

[0109] The present invention provides a Zr-Ti-Hf-Ni-Cu-Co 6-element medium-entropy alloy brazing filler metal. The filler metal's composition by weight is as follows: Ti: 9.5-13.9; Ni: 5.5-9.5; Cu: 5.0-9.5; Co: 2.0-8.5; Hf: 0.0-2.0; and Zr: the balance. The present invention has the following technical advantages: the filler metal has a liquidus temperature between 769°C and 782°C, is easily formed into an amorphous filler metal alloy, and achieves a shear strength of 243-280 MPa for a pure titanium-titanium alloy joint at a brazing temperature of 810°C to 828°C for 10 minutes.

[0110] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0111] In order to further illustrate the present invention, a solder, a preparation method thereof, and a brazing method provided by the present invention are described in detail below with reference to embodiments.

[0112] Example 1-33:

[0113] 1. Selection of raw materials:

[0114] Use high-purity Zr, Ti, Ni, Cu, Co, and Hf elements with a purity of 99.5%-99.9%, and weigh them according to the weight ratio in Table 1; or use high-purity Zr containing 1%-2.5% Hf element, and add Hf element to the raw materials required for the solder through high-purity Zr containing a certain amount of Hf element, and then add pure Hf separately according to the insufficient Hf content in the required composition, while the purity of other elements remains unchanged.

[0115] 2. Preparation of solder:

[0116] The raw materials are arc-melted under inert gas protection to form alloy ingots. To ensure uniform alloy composition, 2-4 melting passes are recommended. The brazing filler metal is prepared using one or more of the following methods: preparing the alloy ingot into alloy powder by argon atomization or plasma rotating electrode atomization; forming the alloy ingot into amorphous alloy foil brazing filler metal by single-roll rapid quenching; or mechanically crushing the alloy ingot to obtain a brazing filler metal block.

[0117] 3. Brazing:

[0118] (1) Material preparation: Prepare the base material of pure titanium or titanium alloy to be welded, and remove oxides, oils or surface attachments on the surface of the base material;

[0119] (2) Assembly: Add one or two forms of brazing filler metals as claimed in claim 4 to the surface of the base material to be welded; place the assembled components into a vacuum brazing furnace with a vacuum degree of not less than 1×10 -3 Pa.

[0120] (3) Brazing process: Use fixtures to control the brazing gap of the interface to be connected in the range of 0 to 0.1 mm, and select the brazing temperature according to the phase change temperature of the matrix material. When the matrix contains pure titanium, the brazing temperature T b is: 810℃-860℃; when the matrix is ​​all titanium alloy, T b Not higher than the phase transition temperature of the corresponding titanium alloy. If vacuum brazing is adopted, the temperature is raised at a rate of 20-40℃ / min to 500℃; then the temperature is raised at a rate of 15-20℃ / min to T bKeep the temperature for 10 to 30 minutes; cool down at a rate of 15-25℃ / min and cool to room temperature along with the furnace. If induction heating brazing is used, heat to T at a rate of 50℃ / min to 100℃ / min. b , keep warm for 1min to 10min, then stop induction heating and cool naturally to room temperature.

[0121] Table 1 Solder composition example

[0122] Regarding Zr-Ti-Hf-Ni-Cu-Co solder and its use method, the solder composition by weight is: Ti: 9.5-13.9; Ni: 5.5-9.5; Cu: 5.0-9.5; Co: 2.0-8.5; Hf: 0.0-2.0; Zr: balance. The solder's liquidus temperature is between 769°C and 782°C.

[0123] Using the components of the solders of Examples 1-33, (1) solder preparation is performed: the alloy raw material for preparing the solder is smelted into an alloy ingot. The solder is then prepared using one or more of the following methods: a) preparing the alloy ingot into an alloy powder solder using an argon atomization powdering method or a plasma rotating electrode atomization method; b) preparing the alloy ingot into an amorphous alloy foil solder using a single-roll rapid quenching method; c) mechanically crushing the alloy ingot to obtain a solder alloy block; d) first preparing alloy solder powder according to the above method, and then pressing and sintering to prepare the desired solder sintered body.

[0124] (2) The matrix materials are TA2-TA2, TA2-TA18, or TA2-TC4 combinations, where TA2 is commercially pure titanium; TA18 has a nominal composition of Ti-3Al-2.5V (by weight); and TC4 has a nominal composition of Ti-6Al-4V (by weight). Amorphous alloy foil strips are cut into the desired shape and fixed to one side of the above-mentioned material combinations using resistance spot welding, with a brazing gap of 0.01-0.08 mm.

[0125] (3) Place the assembled components into a vacuum brazing furnace with a vacuum degree of 4.5×10 -3 Pa, select the appropriate brazing temperature. When the substrate to be welded is TC16 or TC18 titanium alloy, the brazing temperature T b is: 810℃-828℃, and when the matrix is ​​all titanium alloy with a phase change temperature higher than 840℃, the brazing temperature T b It can be: 810℃-828℃, or the brazing temperature T can be appropriately increased b However, it should not be higher than the phase transition temperature of the corresponding titanium alloy. When the matrix is ​​all titanium alloy with a phase transition temperature higher than 840℃, the brazing temperature Tb It can be: 810℃-828℃, or the brazing temperature T can be appropriately increased b However, it should not be higher than the phase transition temperature of the corresponding titanium alloy. When the matrix contains pure titanium, the brazing temperature T b The temperature can be selected arbitrarily within the range of 810℃-860℃.

[0126] The brazing results of Examples 1-33 are as follows: The amorphous alloy foil of the present invention achieves a combination of high strength and good plasticity for brazing pure titanium or combinations of pure titanium and titanium alloys at a brazing temperature of 850-865°C and a holding time of 18-25 minutes: The room temperature tensile strength of TA2-TC4 and TA2-TA18 brazed joints exceeds 530 MPa, while the elongation of the two joints exceeds 10% and 12%, respectively, achieving a strong-plasticity match. Furthermore, the shear strength of the TA2-TA18, TA2-TC16, and TA2-TC18 joints obtained by brazing at 810-828°C reaches 243 MPa-280 MPa at room temperature. By selecting an appropriate holding time, high-quality welding is achieved for TC16-TC16 and TC18-TC18 titanium alloy substrates.

[0127] Table 2 Performance of brazed joints corresponding to Examples 1-33 in Table 1

[0128] The alloy ingot is prepared into alloy powder brazing filler metal by adopting argon gas atomization powder making method or plasma rotating electrode atomization method. The brazing effect with comparable joint performance is also obtained by using the brazing filler metal compositions of Examples 1-33.

[0129] In addition, using the brazing filler metal compositions of Examples 1-33, good welding of all the above-mentioned combined materials was also achieved by induction heating brazing.

[0130] It should be noted that the above process operations can be applied in combination to different degrees. For the sake of simplicity, the implementation methods of various combinations will not be described in detail. Technical personnel in this field can flexibly adjust the order of the above operating steps according to actual needs, or flexibly combine the above steps.

[0131] The above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. The specific embodiments described in the present invention may have different formulas, process names, etc. Any equivalent or simple changes based on the structure, features and principles described in the patent concept of the present invention are included in the patent protection scope of the present invention.

Claims

1. A Zr-Ti-Hf-Ni-Cu-Co six-component medium entropy alloy filler metal, characterized in that, The weight percentages of the solder components are as follows: Ti: 9.5 - 13.9; Ni: 5.5 - 9.5; Cu: 5.0 - 9.5; Co: 2.0 - 8.5; Hf: 0.0 - 2.0; Zr: the balance.

2. The solder according to claim 1, characterized in that, The weight percentages of the solder components are as follows: Ti: 9.5 - 13.0; Ni: 5.5 - 9.0; Cu: 5.0 - 9.5; Co: 3.0 - 8.0; Hf: 0.0 - 2.0; Zr: the balance.

3. The filler metal according to claim 1, wherein The liquidus temperature of the solder is 769 °C - 782 °C; The solder is a medium-entropy alloy solder in one or more of the following shapes: amorphous foil strip, powder, alloy block, or powder sintered body.

4. A preparation method of a Zr-Ti-Hf-Ni-Cu-Co six-component medium entropy alloy filler metal, characterized in that, Including: A) Melting metal raw materials to prepare an alloy ingot; B) Preparing a medium-entropy alloy solder from the alloy ingot; The shape of the medium-entropy alloy solder includes one of amorphous foil strip, powder, alloy block, and powder sintered body.

5. The preparation method according to claim 4, characterized in that, Step B) specifically includes one or more of the following steps: i) Using an argon atomization powder preparation method or a plasma rotating electrode atomization method to prepare the alloy ingot into an alloy powder solder; ii) Using a single-roll rapid solidification method to make the alloy ingot into an amorphous alloy foil strip solder; iii) Mechanically crushing the alloy ingot to obtain a solder alloy block; iv) First preparing a powder solder according to the above method, and then pressing and sintering to prepare a solder sintered body.

6. Application of the Zr-Ti-Hf-Ni-Cu-Co six-component medium-entropy alloy solder according to any one of claims 1 - 3 in soldering pure titanium and / or titanium alloy.

7. A brazing method for pure titanium and / or titanium alloy, characterized in that, Including the following steps: a) Preparation of materials: Prepare the base materials of pure titanium and / or titanium alloy to be welded, and after pretreatment, obtain the pretreated base materials; b) Adding solder to the surface to be welded of the pretreated base materials to obtain an assembled component; the solder is the solder according to any one of claims 1 - 3 or the solder prepared by the preparation method according to any one of claims 4 - 5; c) Performing soldering on the assembled component to obtain the product.

8. According to the soldering method of claim 7, characterized in that The pretreatment in step a) is specifically to remove oxides, oils, or surface contaminants on the surface of the base material; Step b) further includes machining and controlling the soldering gap between the substrates to be soldered to be 0.01 - 0.08 mm through a tooling fixture.

9. The brazing method according to claim 7, characterized in that, The temperature of the soldering in step c) is specifically: When the substrate contains pure titanium, the brazing temperature T b is: 810°C to 860°C; When the base metal to be soldered is TC16 or TC18 titanium alloy, the soldering temperature T b is: 810°C to 828°C; When the substrate is a titanium alloy with a phase transition temperature higher than 840 °C, the brazing temperature T b is: 810 °C to 828 °C, or 10 °C lower than the phase transition temperature of the titanium alloy base material.

10. The brazing method according to claim 9, characterized in that, The soldering method in step c) is vacuum soldering or induction heating soldering; The specific vacuum brazing parameters are as follows: the vacuum degree in the furnace is not lower than 1×10 -3 Pa, the temperature is raised at a rate of 20 - 40°C / min to 500°C; the temperature is continuously raised at a rate of 15 - 25°C / min to T b and held for 10 min - 25 min; the temperature is lowered at a rate of 15 - 25°C / min and cooled in the furnace to room temperature; The specific induction heating brazing parameters are as follows: when the vacuum degree is lower than 2×10 -1 Pa, an inert gas is filled to 70 - 100 KPa, and then it is heated at a heating rate of 50℃ / min - 100℃ / min to T b under the condition of the inert gas, held for 1 min - 10 min, then the induction heating is stopped, and it is naturally cooled to room temperature.

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