A six-element entropy alloy brazing filler metal, a preparation method thereof and a brazing method

Abstract

The application relates to the technical field of brazing, and discloses a Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy brazing filler metal for pure titanium and titanium alloy brazing and a use method. The Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy brazing filler metal provided by the application has the following weight percentage of components: 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 application has the following technical effects: the liquidus temperature of the brazing filler metal is between 769 DEG C and 782 DEG C, the brazing filler metal is easy to be shaped into an amorphous brazing filler metal alloy, and the shear strength of a pure titanium-titanium alloy joint obtained by brazing at a temperature of 810 DEG C-828 DEG C for 10 minutes reaches 243-280 MPa.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of brazing, and particularly relates to a six-element medium-entropy alloy brazing filler metal and a preparation method and a brazing method thereof. BACKGROUND

[0002] Titanium and its alloys have high specific strength and good corrosion resistance, and are one of the main structural materials of contemporary aircraft and engines, which can reduce the weight of the aircraft or engine and improve the 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 35% and Zr element accounts for more than 20%, by weight) brazing filler metal is usually selected as the brazing material to obtain a good joint structure and corresponding high joint strength and good corrosion resistance.

[0003] However, the phase transition temperature T β of pure titanium is 882℃, and the brazing temperature is required to be lower than 882℃ for brazing connection, and for TC16 (Ti-3Al-5Mo-4.5V, by weight) and TC18

[0004] (Ti-5Al-5Mo-5V-1Cr-1Fe, by weight) titanium alloys, their phase transition temperature is as low as 840℃-880℃, that is, the brazing temperature required for brazing connection is lower than 840℃, and in order to ensure that the base material of the welded titanium alloy does not undergo phase transition during brazing, the relatively safe brazing temperature should be no higher than 830℃. Therefore, considering that brazing is generally carried out at a temperature of 30℃-50℃ higher than the melting temperature of the brazing filler metal, the ideal brazing filler metal required for the brazing connection of pure titanium and the above-mentioned titanium alloys including TC6, TC18, etc. has a liquidus temperature of less than 790℃. In addition, it is very important that for the brazing connection of pure titanium and titanium alloys, whether it is an aircraft duct or a thin-walled complex structure of an air or marine heat exchanger, the brazed joint is required to have high strength and good plasticity, so as to ensure the safety and service life of the welded structure.

[0005] However, the liquidus temperature of the current Ti-based or TiZr-based brazing filler metal is relatively high, for example, the liquidus temperature of the typical Ti-15Cu-15Ni alloy (by weight) is high, which is only suitable for brazing the phase transition temperature T βTitanium alloy above 960℃; Ti-13Zr-21Cu-9Ni alloy (wt%) whose liquidus temperature is still high, can only be used for brazing titanium alloy at brazing temperature of 920-940℃; there is also brazing filler metal which can be used for brazing pure titanium and titanium alloy at brazing temperature of about 880℃, but the strength of brazed joint is difficult to exceed 500MPa, and the brazed joint is still obviously brittle. Generally, after the basic weldability of a certain base material is solved, the melting temperature of the filler metal is further reduced to further reduce the required brazing temperature, and the joint strength is also improved, while the brittleness of the brazed joint is also reduced, and improvement or enhancement from the above three aspects is a very challenging technical difficulty. At present, there is still a lack of brazing filler metal material which can be used for brazing pure titanium or pure titanium and titanium alloy at a temperature below 872℃, and which can make the brazed joint have high strength and plasticity. At the same time, under the premise of meeting the mechanical properties of the brazed joint, it is an objective pursued in the field of pure titanium and titanium alloy brazing to reduce the brazing temperature as much as possible to save energy, but at present there is obviously a lack of brazing material which can be used for brazing pure titanium and titanium alloy at a temperature below 830℃, and which can make the brazed joint have high strength. SUMMARY

[0006] Therefore, the purpose of the present application is to provide Zr-Ti-Hf-Ni-Cu-Co six-element entropy alloy brazing filler metal. The brazing filler metal provided by the present application has a liquidus temperature of 769-782℃, can be used for brazing pure titanium or pure titanium and titanium alloy at a temperature of 815-828℃, and the brazed joint obtained has high strength.

[0007] The present application provides a Zr-Ti-Hf-Ni-Cu-Co six-element entropy alloy brazing filler metal, the composition of the brazing filler metal is as follows in terms of weight percentage:

[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 composition of the brazing filler metal is as follows in terms of weight percentage:

[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 brazing filler metal has a liquidus temperature of 769-782℃.

[0012] The brazing filler metal is a six-element entropy alloy brazing filler metal in one or more of the following shapes: amorphous foil, powder, alloy block or powder sintered body.

[0013] The application provides a preparation method of a Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy solder, comprising the following steps:

[0014] A) melting metal raw materials to obtain an alloy ingot;

[0015] B) preparing a medium-entropy alloy solder from the alloy ingot; the shape of the medium-entropy alloy solder comprises one of an amorphous foil strip, a powder, an alloy block and a powder sintered body.

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

[0017] i) preparing the alloy ingot into an alloy powder solder by an argon gas atomization powder preparation method or a plasma rotating electrode atomization method;

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

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

[0020] iv) preparing a powder solder by the above method, and then pressing and sintering to obtain a solder sintered body.

[0021] The application provides application of the Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy solder in any one of the above technical solutions to pure titanium and / or titanium alloy brazing.

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

[0023] a) preparing materials: preparing a base material of pure titanium and / or titanium alloy to be welded, and obtaining a pretreated base material after pretreatment such as test piece processing and surface cleaning;

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

[0025] c) brazing the assembled component, and the brazing is completed.

[0026] Preferably,

[0027] The pretreatment in step a) is specifically removing oxides, oiliness or surface contaminants on the base material;

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

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

[0030] When the base body contains pure titanium, the brazing temperature T b is 810℃-860℃.

[0031] When the base body is TC16 or TC18 titanium alloy, the brazing temperature T b may be 810℃-828℃.

[0032] When the base body is a titanium alloy with a phase transition temperature higher than 840℃, the brazing temperature T b may be 810℃-828℃, or 10℃ lower than the phase transition temperature of the base body.

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

[0034] The vacuum brazing parameters are specifically as follows: the vacuum degree in the furnace is not less than 1×10 -3 Pa, the temperature is raised at a rate of 20-40℃ / min to 500℃, the temperature is continuously raised at a rate of 15-25℃ / min to T b , and the temperature is kept for 10-25min, and the temperature is reduced at a rate of 15-25℃ / min and cooled to room temperature with the furnace.

[0035] The induction heating brazing parameters are specifically as follows: when the vacuum degree is less than 2×10 -1 Pa, inert gas is filled to 70-100KPa, and then heated to T b at a heating rate of 50℃ / min-100℃ / min under the condition of inert gas, kept for 1-10min, and then the induction heating is stopped and naturally cooled to room temperature.

[0036] Compared with the prior art, the application provides a Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy filler, and the weight percentage of the filler composition 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; Zr: the balance. The application has the following technical effects: the liquidus temperature of the filler is between 769℃ and 782℃, the filler is easy to be formed into an amorphous filler alloy, the shear strength of a pure titanium-titanium alloy joint obtained by keeping the brazing temperature at 810℃-828℃ for 10min is 243-280MPa.

[0037] The advantages and beneficial effects of the application are as follows:

[0038] (1) The characteristics and advantages of the brazing filler metal alloy element composition: the multi-element alloy design principle is used, six elements are designed in the application, among which Zr, Ti and Hf can be infinitely mutually soluble, and there is no brittle intermetallic compound formation tendency among them. At the same time, Ni, Cu and Co are added to the brazing filler metal alloy as melting point reducing elements, which can reduce the melting point of the brazing filler metal alloy through Cu-Ni-Zr, Cu-Ni-Ti, Cu-Ti-Zr ternary low-melting eutectic and Co-Ti, Co-Zr binary low-melting eutectic principles, see Figures 1-5 . And through thermodynamic calculation, the mixing entropy ΔS mix (J·K -1 mol -1 ) value of the six-element brazing filler metal alloy of the application is between 9.72-11.32, which meets the thermodynamic condition ΔS mix value falls within the range of 1.0R-1.5R, and it is determined to belong to the medium-entropy alloy brazing filler metal, so it can play a good strengthening and toughening role in the brazing joint of pure titanium and titanium alloy combination.

[0039] (2) The melting temperature of the brazing filler metal alloy is effectively reduced, which can meet the ideal demand that the brazing temperature is not higher than 830℃. In the Zr-Ti-Hf-Ni-Cu-Co six-element brazing filler metal alloy applied, Ni, Cu and Co are used to jointly reduce the melting point, and the effect is much better than that of single Cu, Ni, Co or any two of them, and the actual liquidus temperature of the brazing filler metal is between 769℃-782℃, see Figure 6 , so the brazing can be carried out in the temperature range of 810-828℃, which not only avoids the damage to the performance of the welded base material caused by too high brazing temperature, but also is beneficial to energy saving during the brazing process. This point is more obvious for the energy saving effect of the brazing process corresponding to the low brazing temperature, because for large gap joints (such as 0.3mm-3mm), long time (such as more than 1 hour) diffusion sintering is needed for densification of the brazing joint during brazing connection by simultaneously adding titanium alloy powder and brazing filler metal powder.

[0040] (3) Since the liquidus temperature of the brazing filler metal of the application is lower than 782℃, it is particularly suitable for brazing of TC16 and TC18 titanium alloys with phase transition temperature of 840℃-880℃. In addition, it is also suitable for brazing connection of pure titanium-titanium alloy combination joint, and can be more used for brazing of conventional titanium alloys such as TC4, and the applicable welded titanium alloy base material is wide, and the brazing temperature selection range is also wide, for example, for TA2 pure titanium, the brazing temperature can be in the range of 810℃-870℃, and for TC4 titanium alloy (the phase transition temperature is about 970℃), the brazing temperature can be in the range of 830℃-910℃.

[0041] (4) The brazing filler metal alloy of the present application, its component design fully takes into account the need that it must have good amorphous foil forming ability. Especially for the brazing connection of the multi-layer thin-walled complex structure heat exchanger composed of pure titanium fins and titanium alloy separators, the complete and continuous amorphous alloy foil is used for the pre-welding laying assembly between the layers, which can ensure convenient and efficient assembly and stable and controllable brazing quality. Among the six component elements of the brazing filler metal alloy of the present application, one kind is Zr, Ti, Hf element, and the other kind is Ni, Cu, Co element. They each belong to similar elements within each class, but they belong to different elements between the two classes. See the attached Figure 7 , by their respective appropriate addition amount, the joint melting is carried out. This design idea fully uses the design principles of amorphous alloy "eutectic point criterion, atomic size differentiation, similar and different elements coexistence" and the like. Therefore, under the premise of ensuring low enough melting temperature, the amorphous foil forming ability of the present application is obviously better than that of Zr-Ti-Ni system, ZrTiNiNb(Hf) brazing filler metal. Using single-roll rapid quenching method, amorphous brazing filler metal foil with a width of 25-50mm and a thickness of 25-60μm can be stably obtained. The brazing filler metal foils prepared in different batches all show amorphous characteristics, see the attached Figure 8 . At the same time, because the amorphous foil forming ability of the present application is strong, the yield of the prepared brazing filler metal foil is increased by more than 1.5 times of that of Zr-Ti-Ni system brazing filler metal and Zr-Ti-Ni-Nb(Hf) brazing filler metal.

[0042] (5) Using the brazing filler metal of the present application, for the pure titanium-titanium alloy combined joint, such as the microstructure of the pure titanium-pure titanium, pure titanium-titanium alloy brazed joint under the brazing condition of 825℃-10min is shown in the attached Figure 9 , the joint center zone width is about 30μm, and there is a diffusion reaction zone with a width of about 25-40μm between the joint center zone and the welded pure titanium-titanium alloy base material. However, there is no obvious white Cu-Ti, Cu-Zr, Ni-Ti, Ni-Zr, Co-Ti or Co-Zr intermetallic compound in the whole brazed joint. The brazing filler metal of the present application uses the joint melting method with balanced content of Ni, Cu and Co, which effectively avoids the tendency of forming strong brittle intermetallic compounds in the brazed joint caused by the over-high addition amount of only one kind of element among them. When the brazing holding time is sufficient, Ni, Cu and Co exist in the form of solid solution in the (Zr, Ti, Hf) solid solution, which does not cause joint brittleness, but plays an important role in strengthening the brazed joint. Therefore, using the brazing filler metal of the present application, the brazed joint obtained under suitable brazing process conditions has good strength and plasticity.

[0043] (6) The brazing filler metal has excellent wetting and spreading and gap filling capacity on pure titanium and titanium alloy base, for example, the brazing filler metal shows good wetting on pure titanium TA2 under the condition of vacuum heating at 825℃ for 10 minutes, and the wetting angle is only 37°, as shown in the following figure Figure 10 ; and the gap filling length of the brazing filler metal on titanium alloy TA18 is 75-90mm under the condition of vacuum brazing at 860℃ for 10 minutes, as shown in the following figure Figure 11 .

[0044] (7) The brazing filler metal has the comprehensive effect of high strength and good plasticity on pure titanium and the brazing of pure titanium and titanium alloy combination under the brazing temperature of 850-865℃ and the holding time of 18-25 minutes: the tensile strength of TA2-TC4 and TA2-TA18 brazed joints is all above 530MPa at room temperature, and the elongation of the two kinds of joints is above 10% and 12% respectively, which fundamentally eliminates the brittleness of the brazed joints of the traditional brazing filler metal, and realizes the matching of strength and plasticity of the joints. Meanwhile, the shear strength of TA2-TA18, TA2-TC16 and TA2-TC18 joints obtained by brazing at 810-828℃ is 243MPa-280MPa at room temperature.

[0045] (8) As mentioned above, the brazing filler metal does not contain high-melting-point Nb element, and the content of Hf is controlled to be not higher than 2.0% by weight, and the addition amount of Ni, Cu and Co is balanced, which are all beneficial to smelting the ingot with uniform composition, and further, through the ingot with uniform composition, the amorphous alloy foil brazing filler metal with uniform composition and no segregation is easily obtained by single-roll rapid quenching method. On the other hand, through the ingot with uniform composition, the powder brazing filler metal with uniform composition is obtained by argon atomization and plasma rotating electrode atomization method.

[0046] (9) The brazing filler metal alloy itself has the characteristics of high alloying, and the diffusion of Cu, Ni and Co elements to the pure titanium and titanium alloy base and the diffusion of Ti element in the pure titanium and titanium alloy base to the brazing seam area occur during brazing, so the brazed joint is a TiZr(Hf) based super solid solution, and the content of Cu, Ni and Co elements is relatively low, so the brazed joint not only has good mechanical properties, but also has good corrosion resistance due to the high alloying characteristics of the brazed joint. BRIEF DESCRIPTION OF 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] Figure 4 Co-Ti binary phase diagram;

[0051] Figure 5 Co-Zr binary phase diagram;

[0052] Figure 6 Two typical solid-liquid phase line temperatures of meso-entropy alloy filler metal;

[0053] Figure 7 Position diagram of composition elements of meso-entropy alloy filler metal in periodic table;

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

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

[0056] Figure 10 Wetting cross section of filler metal on pure titanium TA2 under the condition of vacuum heating at 825℃ for 10min;

[0057] Figure 11 The gap filling length of meso-entropy alloy filler metal on titanium alloy TA18 reaches 75-90mm (wedge-shaped gap, total length of 93mm, 1mm high at one end, brazing at 860℃ for 10min). DETAILED DESCRIPTION

[0058] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0059] In the present application, the term "and / or" describes the association relationship of associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural.

[0060] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single item or multiple items.

[0061] It should be understood that the size of the sequence number of the above processes does not mean the order of execution in various embodiments of the present application, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to 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 application provides a Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy filler metal, and the weight percentage of the filler metal composition is:

[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 application, the preferred weight percentage of the filler metal composition is:

[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 filler metal is 769-782 DEG C.

[0067] The present application finds that the use of Ni, Cu, and Co three elements combined with melting reduction has much better effect than the use of single Cu, Ni, Co or any two of them together, and the actual liquidus temperature of the filler metal is between 769-782 DEG C, which is suitable for a wide range of welded titanium alloy base materials, and the brazing temperature can be selected in a wide range.

[0068] In some embodiments, the titanium-containing material can include, but is not limited to: a ribbed wall plate structure of pure titanium material and / or titanium alloy material; a thin-walled structure of pure titanium material and / or titanium alloy material; a sandwich structure of pure titanium material and / or titanium alloy material, any structure of titanium alloy-titanium alloy. The filler metal is a medium-entropy alloy filler metal in one or more of the following shapes: amorphous foil, powder, alloy block or powder sintered body.

[0069] The present application designs 6 constituent elements, among which Zr, Ti, and Hf are three elements that can be infinitely mutually soluble, and there is no brittle intermetallic compound formation tendency among them. Meanwhile, Ni, Cu, and Co are three elements added as melting reduction elements in the filler metal alloy, which achieve the effect of reducing the melting point of the filler metal alloy through the principles of Cu-Ni-Zr, Cu-Ni-Ti, Cu-Ti-Zr ternary low-melting eutectic and Co-Ti, Co-Zr binary low-melting eutectic. And through thermodynamic calculation, the mixing entropy ΔS of the six-element filler metal alloy of the present application is mix (J·K-1 mol -1 ) value is between 9.72 and 11.32, satisfying the thermodynamic condition ΔS mix value falls in the range of 1.0R-1.5R, and it is determined to belong to the medium-entropy alloy filler metal, and thus can play a good strengthening and toughening effect in the brazed joint of pure titanium, pure titanium and titanium alloy combination.

[0070] The application provides a preparation method of a Zr-Ti-Hf-Ni-Cu-Co six-element medium-entropy alloy filler metal, comprising the following steps:

[0071] A) melting metal raw materials to prepare an alloy ingot;

[0072] B) preparing a medium-entropy alloy filler metal from the alloy ingot; the shape of the medium-entropy alloy filler metal comprises one of an amorphous foil, a powder, an alloy block and a powder sintered body.

[0073] The application first melts metal raw materials to prepare an alloy ingot.

[0074] High-purity Zr, Ti, Ni, Cu, Co and Hf elements with a purity of 99.5%-99.9% are used and weighed according to the weight ratio; or high-purity Zr containing 1%-2.5% Hf elements is used, and Hf elements are added to the required raw materials of the filler metal by adding high-purity Zr containing a certain amount of Hf elements, and pure Hf is additionally added according to the required Hf content, and the purity of other elements remains unchanged.

[0075] The application preferably adopts an electric arc melting method to melt the raw materials into an alloy ingot under inert gas protection, and the recommended parameters of the electric arc melting are as follows: the melting chamber is vacuumized to 2*10 -1 Pa, then argon is filled to standard atmospheric pressure, the arc current is 80A, the stable melting current is 200A, the melting time is 13-25s, and the melting is recommended to be performed for 2-4 times to ensure the uniformity of the alloy composition.

[0076] The alloy ingot is prepared into a medium-entropy alloy filler metal.

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

[0078] i) the alloy ingot is prepared into alloy powder brazing filler by argon gas atomization or plasma rotating electrode atomization method; the parameters of the argon gas atomization method include that the bar stock is clamped by a clamp and placed in a conical induction coil in an inert gas protection state of argon or helium; the height of the conical induction coil is 500-700 mm, the lower end diameter is 40-65 mm, and the taper angle is 40-65°; the power of the power supply device for providing current for the induction coil is 10-23 KW, and the frequency is 3500 Hz; the bar stock feeding 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 include that the brazing filler metal alloy bar stock has a diameter of 30-60 mm, the rotating speed is 20000-35000 r / min, and the feeding speed is 2-5 mm / min.

[0080] ii) the alloy ingot is prepared into amorphous alloy foil brazing filler by single-roller rapid quenching method; the parameters of the single-roller rapid quenching method include that the bar stock is placed in a quartz crucible in an inert gas protection state of argon or helium, and the quartz tube crucible is placed in a ring induction coil; the induction coil has a height of 300-600 mm and a lower end tube width of 30-50 mm°; the bar stock feeding speed is 0.2-0.5 m / s; the single-roller rotating speed is 1300-1800 r / min; and the jet pressure is 50-70 KPa.

[0081] iii) the alloy ingot is mechanically broken to obtain brazing filler alloy blocks;

[0082] The parameters of the mechanical breaking include that the brazing filler metal alloy is manually knocked by an iron hammer with a weight of 10 kg-30 kg until broken, or is broken by a wire cutting method.

[0083] iv) the powder brazing filler is prepared by the above method, and then is pressed and sintered to obtain a brazing filler sintered body.

[0084] The pressing and sintering includes that the brazing filler powder has a particle size of-150 mesh, the pressing pressure is 60-80 kN, and the sintering specification in a vacuum furnace is a vacuum degree of 8x10 -3 Pa, a temperature of 730-750℃, and a holding time of 20-40 min.

[0085] The application provides application of the Zr-Ti-Hf-Ni-Cu-Co six-element entropy alloy brazing filler in pure titanium and / or titanium alloy brazing.

[0086] The Zr-Ti-Hf-Ni-Cu-Co six-element entropy alloy brazing filler metal can be used for brazing between pure titanium and pure titanium, brazing between pure titanium and titanium alloy, and brazing between titanium alloy and titanium alloy, and good effects can be achieved.

[0087] The application provides a brazing method for pure titanium and / or a titanium alloy, and comprises the following steps.

[0088] a) preparing base materials of pure titanium and / or a titanium alloy to be welded, and obtaining pretreated base materials after pretreatment;

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

[0090] c) brazing the assembled component.

[0091] The pure titanium and / or the titanium alloy in the application include pure titanium-pure titanium, pure titanium-titanium alloy and titanium alloy-titanium alloy.

[0092] The brazing method for pure titanium and / or a titanium alloy provided by the application first comprises preparing materials.

[0093] The base materials of pure titanium and / or a titanium alloy to be welded are prepared, and pretreated base materials are obtained after pretreatment; the pretreatment specifically comprises removing oxides, oiliness or surface contaminants on the base materials; the application does not limit the specific removal method, and the skilled in the art is familiar with it.

[0094] The brazing filler metal is added to a surface to be welded of the pretreated base materials to obtain an assembled component; the brazing filler metal is the brazing filler metal in the above technical solution or the brazing filler metal prepared by the preparation method in the above technical solution.

[0095] Preferably, the brazing gap between the base materials to be brazed is controlled to be 0.01-0.08 mm by a tooling fixture.

[0096] The application does not limit how the tooling fixture controls the brazing gap, and the skilled in the art is familiar with it.

[0097] The assembled component is brazed, and the brazing method for pure titanium and / or a titanium alloy is obtained.

[0098] The assembled component is placed into a vacuum brazing furnace, and the vacuum degree in the furnace is not less than 1*10 -3 Pa.

[0099] The brazing temperature is selected according to the phase transition temperature of the base material.

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

[0101] When the base material contains pure titanium, the brazing temperature T bis: 810℃~860℃;

[0102] When the base body is all titanium alloy, then T b is not higher than the phase transition temperature of the corresponding titanium alloy. The phase transition temperature of the present application is the transition temperature between the α and β phases of the titanium alloy.

[0103] When the base body is TC16 or TC18 titanium alloy, then the brazing temperature T b is: 810℃~828℃;

[0104] When the base body is TA18 or TA2 titanium alloy with a phase transition temperature higher than 840℃, then the brazing temperature T b is set to: 810℃~830℃, and can also be set to 810℃~860℃. When the base body is TC4 titanium alloy, the brazing temperature T b can be set to: 810℃~890℃.

[0105] The brazing method described in the present application is vacuum brazing or induction heating brazing;

[0106] In some embodiments of the present application, the vacuum brazing parameters are specifically: the vacuum degree in the furnace is not less than 1×10 -3 Pa, the temperature is raised at a rate of 20~40℃ / min to 500℃, the temperature is continuously raised at a rate of 15~25℃ / min to T b , and is kept for 10min~30min, and the temperature is lowered at a rate of 15~25℃ / min, and is cooled to room temperature with the furnace.

[0107] In some embodiments of the present application, the induction heating brazing parameters are specifically: under the condition of inert gas, the temperature is raised to T b at a rate of 50℃ / min~100℃ / min, is kept for 1min~10min, the induction heating is stopped, and is naturally cooled to room temperature.

[0108] The brazing filler metal of the present application adopts a combined melting method with balanced contents of Ni, Cu and Co, which effectively avoids the tendency of forming strong brittle intermetallic compounds in the brazed joint due to the excessive addition of only one kind of element in the process of melting. The brazing filler metal of the present application has good strength and plasticity under suitable brazing process conditions. The brazing filler metal of the present application has strong wetting and spreading ability and gap filling capacity on pure titanium and titanium alloy base body.

[0109] The application provides a Zr-Ti-Hf-Ni-Cu-Co six-element entropy alloy brazing filler metal, and the weight percentage of the brazing filler metal composition 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; Zr: the balance. The application has the following technical effects: the liquidus temperature of the brazing filler metal is between 769 DEG C and 782 DEG C, the brazing filler metal is easy to be formed into an amorphous brazing filler metal alloy, and the shear strength of a pure titanium-titanium alloy joint obtained by brazing at a brazing temperature of 810 DEG C-828 DEG C for 10 minutes reaches 243-280 MPa.

[0110] It should be understood that the size of the sequence number of the above processes in various embodiments of the application does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the application.

[0111] In order to further illustrate the application, the brazing filler metal provided by the application, the preparation method and the brazing method are described in detail below in combination with the embodiments.

[0112] Embodiment 1-33:

[0113] 1. Selection of raw materials:

[0114] High-purity Zr, Ti, Ni, Cu, Co and Hf elements with a purity of 99.5%-99.9% are used, and the weight ratio is weighed according to Table 1; or high-purity Zr containing 1%-2.5% Hf elements is used, and Hf elements are added to the required raw materials of the brazing filler metal by high-purity Zr containing a certain amount of Hf elements, and pure Hf is additionally added according to the required Hf content, and the purity of other elements remains unchanged.

[0115] 2. Preparation of the brazing filler metal:

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

[0117] 3. Brazing:

[0118] (1) Preparation of materials: preparing the base material of the pure titanium or titanium alloy to be welded, removing the oxides, oiliness or surface attachments on the surface of the base material;

[0119] (2) Assembly: Put one or two kinds of filler metals on the surface of the base material to be welded; put the assembled component into a vacuum brazing furnace, and the vacuum degree in the furnace is not less than 1 x 10 -3 Pa.

[0120] (3) Brazing process: control the brazing gap of the interface to be connected in the range of 0-0.1 mm through a fixture, and select the brazing temperature according to the phase transition temperature of the base material. When the base material contains pure titanium, the brazing temperature T b is: 810℃-860℃; when the base material is all titanium alloy, T b is 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, and the temperature is raised to 500℃; then the temperature is raised at a rate of 15-20℃ / min, and the temperature is raised to T b and is kept for 10-30 min; the temperature is lowered at a rate of 15-25℃ / min, and the furnace is cooled to room temperature. If induction heating brazing is adopted, the temperature is raised at a rate of 50℃ / min-100℃ / min to T b , and is kept for 1-10 min, and then the induction heating is stopped, and the temperature is naturally cooled to room temperature.

[0121] Table 1 Composition of filler metal examples

[0122]

[0123]

[0124] For the Zr-Ti-Hf-Ni-Cu-Co filler metal and the use method, the weight percentage of the filler metal composition 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 liquidus temperature of the filler metal is between 769℃ and 782℃.

[0125] Using the composition of the filler metal of examples 1-33, (1) filler metal preparation: the alloy raw material for preparing the filler metal is melted into an alloy ingot. Then the filler metal is prepared by one or more of the following methods: a) the alloy ingot is prepared into an alloy powder filler metal by argon atomization powdering method or plasma rotating electrode atomization method; b) the alloy ingot is prepared into an amorphous alloy foil filler metal by single-roller rapid quenching method; c) the alloy ingot is mechanically broken to obtain a filler metal alloy block; d) the alloy filler powder is prepared according to the above method, and then the required filler metal sintered body is prepared by pressing and sintering.

[0126] (2) The base material is TA2-TA2, TA2-TA18, TA2-TC4 material combination, TA2 is industrial pure titanium; TA18 nominal composition is: Ti-3Al-2.5V (wt%); TC4 nominal composition is: Ti-6Al-4V (wt%). The amorphous alloy foil is cut into the required shape, and is fixed on one side of the above various material combinations by resistance spot welding method, and the brazing gap is 0.01-0.08mm.

[0127] (3) The assembled component is placed into a vacuum brazing furnace, the vacuum degree in the furnace is 4.5x10 -3 Pa, and a suitable brazing temperature is selected. When the base to be welded is TC16 or TC18 titanium alloy, the brazing temperature T b is: 810℃-828℃, and when the base is all titanium alloy with phase transition temperature higher than 840℃, the brazing temperature T b may be: 810℃-828℃, or the brazing temperature T b may be appropriately increased, but should not be higher than the phase transition temperature of the corresponding titanium alloy. When the base is all titanium alloy with phase transition temperature higher than 840℃, the brazing temperature T b may be: 810℃-828℃, or the brazing temperature T b may be appropriately increased, but should not be higher than the phase transition temperature of the corresponding titanium alloy. When the base contains pure titanium, the brazing temperature T b may be completely selected at will in a large range of 810℃-860℃.

[0128] The brazing effect of examples 1-33 is: the amorphous alloy foil of the brazing filler metal of the application, for the brazing of pure titanium and the combination of pure titanium and titanium alloy, obtains the comprehensive effect of high strength and good plasticity at the brazing temperature of 850-865℃ and the holding time of 18-25 minutes: the tensile strength of TA2-TC4, TA2-TA18 brazed joints at room temperature is all above 530MPa, and the elongation of the two kinds of joints is respectively above 10% and 12%, realizing the matching of the strength and plasticity of the joints. At the same time, the shear strength of TA2-TA18, TA2-TC16, TA2-TC18 joints obtained by brazing at 810-828℃ reaches 243MPa-280MPa at room temperature. By selecting a suitable holding time, the high-quality welding of TC16-TC16, TC18-TC18 titanium alloy is realized.

[0129] Table 2 The brazed joint performance corresponding to examples 1-33 in table 1

[0130]

[0131]

[0132] The alloy ingot is prepared into alloy powder brazing material by argon atomization powdering method or plasma rotating electrode atomization method, and the brazing effect of the joint performance is also obtained by using the brazing material compositions of Examples 1-33.

[0133] In addition, using the brazing material compositions of Examples 1-33, the good welding of all the above-mentioned combined materials is also achieved by using the induction heating brazing method.

[0134] It should be noted that the above process operations can be combined to different degrees. In order to be simple, the implementation modes of various combinations are not described again, and the order of the above operation steps can be flexibly adjusted or the above steps can be flexibly combined by those skilled in the art according to actual needs.

[0135] The above examples are only used to illustrate the technical solutions of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application. The specific examples described in the present application, the names of the formula, process, etc. can be different. Any equivalent or simple change based on the structure, features and principles of the patent concept of the present application is included in the patent protection scope of the present application.

Claims

1. A Zr-Ti-Hf-Ni-Cu-Co six-element medium entropy alloy solder, characterized by, The weight percentage of the brazing filler metal composition is: Ti: 9.5-13.9; Ni: 5.5-9.5; Cu: 5.0-9.5; Co: 2.0-8.5; Hf: 0.6-2.0; Zr: balance.

2. The brazing material according to claim 1, characterized in that, The weight percentage of the brazing filler metal composition is: Ti: 9.5-13.0; Ni: 5.5-9.0; Cu: 5.0-9.5; Co: 3.0-8.0; Hf: 0.6-2.0; Zr: balance.

3. The brazing material according to claim 1, characterized in that, The liquidus temperature of the brazing filler metal is 769℃-782℃; The brazing filler metal is a multi-entropy alloy brazing filler metal in one or more of the following shapes: amorphous foil strip, powder, alloy block, or powder sintered body.

4. A method of producing the Zr-Ti-Hf-Ni-Cu-Co six-element entropy alloy solder of claim 1, characterized by, Comprising: A) melting metal raw materials to prepare an alloy ingot; B) preparing a multi-entropy alloy brazing filler metal from the alloy ingot; The shape of the multi-entropy alloy brazing filler metal includes one of amorphous foil strip, powder, alloy block, or 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 argon gas atomization powdering method or plasma rotating electrode atomization method to prepare the alloy ingot into alloy powder brazing filler metal; ii) using single-roll rapid quenching method to prepare the alloy ingot into amorphous alloy foil strip brazing filler metal; iii) mechanically crushing the alloy ingot to obtain brazing filler metal alloy block; iv) first preparing powder brazing filler metal according to the above method, and then pressing and sintering to prepare brazing filler metal sintered body.

6. The application of the Zr-Ti-Hf-Ni-Cu-Co six-element multi-entropy alloy brazing filler metal according to any one of claims 1-3 in the brazing of pure titanium and / or titanium alloy.

7. A brazing method of pure titanium and / or titanium alloy, characterized by, Comprising the following steps: a) preparing the base material of the pure titanium and / or titanium alloy to be welded, and after pretreatment, obtaining a pretreated base material; b) adding brazing filler metal to the surface of the pretreated base material to be welded to obtain an assembled component; the brazing filler metal is the brazing filler metal according to any one of claims 1-3 or prepared by the preparation method according to any one of claims 4-5; c) brazing the assembled component, and the brazing is completed.

8. The brazing method according to claim 7, characterized in that: The pretreatment of step a) specifically removes the oxides or oil on the surface of the base material; Step b) further includes mechanical processing and controlling the brazing gap between the base bodies to be brazed to be 0.01-0.08mm by using a tool clamp.

9. The brazing method according to claim 7, characterized by, The brazing temperature of step c) is specifically: When the base body contains pure titanium, the brazing temperature T b is: 810℃~860℃; When the base to be welded is TC16 or TC18 titanium alloy, the brazing temperature T b is: 810℃~828℃; When the base body is a titanium alloy with a phase transition temperature higher than 840℃, the brazing temperature T b is: 810℃~828℃, or 10℃ lower than the phase transition temperature of the titanium alloy base material.

10. The brazing method according to claim 9, characterized by The brazing method of step c) is vacuum brazing or induction heating brazing; The vacuum brazing parameters are specifically: the vacuum degree in the furnace is not less than 1*10 -3 Pa, the temperature is raised at a rate of 20-40 ℃ / min to 500 ℃, the temperature is continuously raised at a rate of 15-25 ℃ / min to T b brazing temperature, and the temperature is kept for 10-25 min, the temperature is lowered at a rate of 15-25 ℃ / min, and the furnace is cooled to room temperature. The induction heating brazing parameters are specifically: vacuum degree is less than 2*10 -1 Pa, inert gas is filled to 70~100KPa, then heated to T b under the condition of inert gas at a heating rate of 50℃ / min~100℃ / min, kept for 1min~10min, then induction heating is stopped, and natural cooling is performed to room temperature.

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