High-entropy alloy brazing filler metal for nickel-based powder high-temperature alloy connection and preparation method and application of high-entropy alloy brazing filler metal

Abstract

The invention provides high-entropy alloy brazing filler metal for nickel-based powder high-temperature alloy connection and a preparation method and application of the high-entropy alloy brazing filler metal, and belongs to the technical field of metal welding. The high-entropy alloy brazing filler metal is composed of, by atomic ratio, 15%-20% of Co, 15%-18% of Cr, 5%-8% of Al, 4%-7% of Mo, 8%-10% of Hf + Zr, 3%-5% of Ge + Ga, 2%-3% of Ti, 2%-5% of Pd, 0.5% of Os, 0.15% of Mg, 0.05% of Ce, 0.03% of La and the balance Ni, the purity of the elements is larger than 99.99 wt.%, the high-entropy alloy brazing filler metal is arranged between an upper nickel-based powder high-temperature alloy layer and a lower nickel-based powder high-temperature alloy layer for brazing, compared with traditional brazing filler metal, the wetting effect is better, and the service life of the high-entropy alloy brazing filler metal is prolonged. And precipitation of a brittle phase can be inhibited under the combined action of mechanisms such as a high-entropy effect, component synergy and solution strengthening, the comprehensive mechanical property of the joint is improved, and the production requirements of new-generation engine parts in the aerospace field are met.

Description

Technical Field

[0001] The present invention relates to the technical field of metal welding, and in particular to a high-entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys, and a preparation method and application thereof. Background Art

[0002] Currently, advanced aircraft engines are developing towards high thrust-to-weight ratios and high thrust, placing higher demands on engine materials. Powder superalloys (typical materials such as FGH99) have excellent high-temperature strength and oxidation resistance, making them the preferred material for manufacturing new-generation aircraft engine components. However, the total alloying element content of powder superalloys usually exceeds 50wt.%, and their deformation resistance is high, making them typical difficult-to-weld materials. Among the welding methods for this type of material, traditional fusion welding is prone to weld crack defects, and solid-phase diffusion welding has a low weld rate. Brazing, on the other hand, has the advantages of low heating temperature, little impact on the structure and properties of the parent material, small overall deformation of the weldment, and high dimensional accuracy of the weldment. Therefore, it is suitable for the production of new-generation engine components in the aerospace field.

[0003] As a new generation of brazing materials, high entropy alloy brazing filler metals show significant technical advantages and application potential compared with traditional brazing fillers. Traditional brazing fillers are prone to form brittle intermetallic compounds at the interface, resulting in a decrease in joint strength. Therefore, designing a high entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys has become a key issue. Summary of the Invention

[0004] In view of the deficiencies in the background technology, the present invention mainly solves the problem of poor mechanical properties of nickel-based powder high-temperature alloy brazing joints using traditional brazing filler metals due to the presence of more brittle phases.

[0005] On one hand, the present invention provides a high-entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys. The high-entropy alloy brazing filler metal is composed of the following elements in the following atomic ratio: Co 15-20%, Cr 15-18%, Al 5-8%, Mo 4-7%, Hf+Zr 8-10%, Ge+Ga 3-5%, Ti 2-3%, Pd 2-5%, Os 0.5%, Mg 0.15%, Ce 0.05%, La 0.03%, with the balance being Ni, and the element purity is greater than 99.99wt.%.

[0006] A second aspect of the present invention provides a method for preparing a high-entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys. The method for preparing the high-entropy alloy brazing filler metal is as follows: Step 1: Weigh pure metal element particles Co, Cr, Al, Mo, Hf, Zr, Ge, Ga, Ti, Pd, Os, Mg, Ce, and La according to the atomic ratio of the constituent elements of the high-entropy alloy solder, wash and dry them, place them in a vacuum planetary mixer, and mix them in stages for 2 hours to obtain a mixed powder; Step 2: placing the mixed powder in a tungsten crucible and preparing a high entropy alloy ingot by vacuum arc melting; Step 3: The high entropy alloy ingot is subjected to multiple hot rolling and multiple cold rolling to obtain a cold-rolled sheet, which is cut into sections and then polished using a grinder to obtain a target intermediate layer, and then polished, cleaned, and dried to obtain the high entropy alloy brazing material.

[0007] Preferably, the staged mixing in step 1 includes: The first stage is pre-mixing, mixing at 20%-30% of the revolution speed for 15 minutes; The second stage, main mixing, is mixing at 70%-80% of the revolution speed for 90 minutes; The third stage is stable mixing, mixing at 20%-30% of the revolution speed for 15 minutes to obtain the mixed powder.

[0008] Preferably, in the process of preparing the high entropy alloy ingot by vacuum arc melting in step 2, the vacuum degree during melting is , smelting times>3 times.

[0009] Preferably, the reduction rate of a single pass of the multi-pass hot rolling is 5%-8%, and the reduction rate of a single pass of the multi-pass cold rolling is 8%-11%; the thickness of the cold-rolled sheet is 100μm-200μm; the thickness of the target intermediate layer is 40μm-80μm, and the thickness error is ±3μm.

[0010] A third aspect of the present invention provides an application of the above-mentioned high entropy alloy brazing material in brazing nickel-based powder high-temperature alloys, wherein the high entropy alloy brazing material serves as an intermediate layer to connect the nickel-based powder high-temperature alloys.

[0011] Preferably, the nickel-based powder high-temperature alloy is one or more of FGH99 nickel-based high-temperature alloy, FGH95 nickel-based high-temperature alloy, FGH96 nickel-based high-temperature alloy, FGH97 nickel-based high-temperature alloy, and FGH98 nickel-based high-temperature alloy.

[0012] Preferably, in the process of connecting the nickel-based powder high-temperature alloy as the intermediate layer, the high-entropy alloy brazing material is placed between the upper and lower layers of nickel-based powder high-temperature alloy, and then placed in a vacuum brazing furnace for brazing.

[0013] Preferably, the brazing adopts a segmented heating and pressurizing method, and the specific process is as follows: in the first section, the vacuum brazing furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept warm for 10 minutes; in the second section, the temperature is increased from 300°C to 700°C at a rate of 10°C / min and kept warm for 10 minutes; in the third section, the temperature is increased from 700°C to 900°C at a rate of 10°C / min and kept warm for 10 minutes; in the fourth section, the temperature is increased from 900°C to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth section, the temperature is kept warm at the welding temperature of 1150°C for 45 minutes, a pressure of 0.03MPa is applied, and then the furnace is cooled to room temperature; the vacuum degree of the vacuum brazing furnace is .

[0014] Preferably, before brazing in a vacuum brazing furnace, the nickel-based powder high-temperature alloy is ground and polished with sandpaper and polishing liquid, then ultrasonically cleaned in anhydrous ethanol, rinsed with deionized water, and then cleaned with anhydrous ethanol and dried.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The high entropy alloy brazing filler metal for nickel-based powder high-temperature alloy connection proposed in the present invention has a high entropy effect compared to the traditional brazing filler metal for nickel-based high-temperature alloy brazing. Among its constituent elements, Co replaces part of Ni in the traditional nickel-based brazing filler metal, and while forming an infinite solid solution with Ni, it can reduce the solubility of elements such as Al and Ti in the matrix, increase the amount of strengthening phase, and thus improve the overall performance of the alloy. Among them, Mo maintains the thermal strength of the brazing filler metal on the one hand, and can refine the grains and reduce the cost on the other hand. In addition, compared with W, its melting point is lower, which is more conducive to the melting of the brazing filler metal; Ge and Ga replace the melting-reducing elements B and Si added in the traditional brazing filler metal. While reducing the melting point, Ge itself has a certain affinity for oxygen and will preferentially combine with oxygen at high temperature, thereby improving the oxidation resistance of the joint. Ga can partially replace Al, adjust the lattice mismatch of the γ' phase, and improve its stability and strengthening effect; Zr, Hf It is an element that strongly forms the γ' phase. Zr tends to segregate at the grain boundaries, which can fill vacancies and enhance grain boundary strength. Hf has a high melting point and can promote the dispersion and distribution of carbides while improving the thermal strength of the joint, thereby improving the stability of grain boundaries and carbides. Pd can improve the wettability of the brazing filler metal on the base material and has excellent oxidation resistance and corrosion resistance at high temperatures. Pd can also form a solid solution with Ni to enhance the mechanical properties of the joint. The trace addition of Mg helps to improve the toughness of the brazed joint and can preferentially react with oxygen at high temperatures to exhibit oxidation resistance. Os atoms can dissolve into the nickel matrix, hindering dislocation movement through lattice distortion, and also promote the formation of dense Cr and Al oxide films, thereby improving the oxidation resistance of the joint at high temperatures. The combined action of Ce and La refines the grains and produces a composite microalloying effect with elements such as Zr and Ti, reducing the tendency to crack and contributing to the improvement of creep properties.

[0016] The high-entropy alloy brazing filler metal proposed in the present invention is used to connect nickel-based powder high-temperature alloys. Compared with traditional brazing fillers, it has a better wetting effect and can inhibit the precipitation of brittle phases under the combined action of high-entropy effect, component synergy, solid solution strengthening and other mechanisms, thereby improving the comprehensive mechanical properties of the joint and meeting the production needs of the new generation of engine components in the aerospace field. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a microstructure diagram of the interface of the high entropy alloy brazing material provided in Example 1 of the present invention connected to the FGH99 nickel-based high-temperature alloy.

[0018] Figure 2 This is a microstructure diagram of the interface of FGH99 nickel-based high-temperature alloy connected with conventional solder provided in Comparative Example 1 of the present invention.

[0019] Figure 3 This is a microstructure diagram of the interface of FGH99 nickel-based high-temperature alloy connected with conventional solder provided in Comparative Example 2 of the present invention. Specific implementation methods

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0021] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless otherwise explicitly defined herein.

[0022] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] The present invention provides a high-entropy alloy brazing filler metal for nickel-based powder high-temperature alloy connection, which is specifically composed of the following elements in atomic ratio: Co 15-20%, for example, 15%, 16%, 17%, 18%, 19%, and 20%; Cr 15-18%, for example, 15%, 16%, 17%, and 18%; Al 5-8%, for example, 5%, 6%, 7%, and 8%; Mo 4-7%, for example, 4%, 5%, 6%, and 7%; Hf+Zr8-10%, for example, 8%, 9%, and 10%; Ge+Ga 3-5%, for example, 3%, 4%, and 5%; Ti 2-3%, for example, 2%, and 3%; Pd 2-5%, for example, 2%, 3%, 4%, and 5%; Os 0.5%; Mg 0.15%; Ce 0.05%; La 0.03%, and the balance is Ni, and the element purity is greater than 99.99wt.%.

[0024] The preparation process of high entropy alloy solder is as follows: Step 1: Weigh pure metal element particles Co, Cr, Al, Mo, Hf, Zr, Ge, Ga, Ti, Pd, Os, Mg, Ce, and La according to the atomic ratio of the constituent elements of the above-mentioned high-entropy alloy solder. Then, clean the surface of the metal particles with a 5wt.% NaHCO3 solution to remove oil and impurities, rinse with deionized water, and finally clean the surface with anhydrous ethanol and place in a drying oven. Dry at 150°C for 90 minutes. Place the cleaned metal particles in a vacuum planetary mixer according to the required atomic ratio and mix them in stages for 2 hours. The mixed powder is obtained in the following stages: stage 1, pre-mixing, mixing at a relatively low speed, i.e., 20%-30% of the revolution speed (the revolution speed is set to 600 rpm) for 15 minutes to preliminarily disperse the powders of each element; stage 2, main mixing, mixing at a relatively high speed, i.e., 70%-80% of the revolution speed, for 90 minutes to achieve high uniformity of powder mixing; stage 3, stable mixing, mixing at a relatively low speed, i.e., 20%-30% of the revolution speed, for 15 minutes to prevent density stratification caused by centrifugal force and stabilize the mixing effect; wherein, the revolution speed is 600 rpm; Step 2: Place the obtained mixed powder in a tungsten crucible and use vacuum arc melting method. The vacuum degree should be maintained at The melting times should be at least 3 times, and electromagnetic stirring should be performed. After the melting is completed, the furnace is vacuum cooled to obtain a high entropy alloy ingot. Step 3: The high entropy alloy ingot is first subjected to multiple hot rolling, and the reduction rate of each pass is controlled within 5-8%. The high entropy alloy ingot obtained after hot rolling is then cut into a flat rectangular parallelepiped of a certain size (such as 30mm×30mm×5mm) by an electric spark wire cutting machine, and then subjected to multiple cold rolling to obtain a cold-rolled sheet with a thickness of preferably 100μm-200μm. For example, the thickness of the cold-rolled sheet can be 100μm, 120μm, 150μm, 170μm, and 200μm; the reduction rate of each pass of the multiple cold rolling is controlled within 8%-11%. The cold-rolled sheet is then cut into sections using an electric spark wire cutting machine and polished with a high-speed precision transverse thinning grinder to a thickness of preferably 40 μm-80 μm, for example, 40 μm, 50 μm, 60 μm, 70 μm, or 80 μm, with a thickness error controlled within ±3 μm. The polished sheet is then mechanically polished using a silica polishing liquid with a particle size of 150 nm. After polishing, it is ultrasonically cleaned with anhydrous ethanol for 15 minutes and dried in an inert gas protection dryer for 15 minutes. After drying, it is taken out in time to obtain a high-entropy alloy solder.

[0025] The process of brazing nickel-based powder high-temperature alloy using the high-entropy alloy brazing filler metal prepared by the present invention is as follows: Before welding in a vacuum brazing furnace, the base material FGH99 was ground and polished using sandpaper with mesh sizes of 160#, 240#, 400#, 600#, 800#, 1000#, 1500#, and 2000# and a silica polishing liquid with a particle size of 150nm. After the grinding and polishing treatment, the base material nickel-based powder high-temperature alloy was ultrasonically cleaned in anhydrous ethanol for 15 minutes, then rinsed with deionized water, and finally cleaned with anhydrous ethanol and placed in a drying oven for drying at 150°C for 20 minutes to obtain the pretreated base material. Subsequently, the prepared high entropy alloy brazing filler metal is placed between the upper and lower layers of nickel-based powder high-temperature alloy, and then placed in a vacuum brazing furnace for brazing; The specific process of brazing is as follows: in the first stage, the vacuum brazing furnace is heated from room temperature to 300℃ at a rate of 10℃ / min and kept warm for 10 minutes; in the second stage, the temperature is increased from 300℃ to 700℃ at a rate of 10℃ / min and kept warm for 10 minutes; in the third stage, the temperature is increased from 700℃ to 900℃ at a rate of 10℃ / min and kept warm for 10 minutes; in the fourth stage, the temperature is increased from 900℃ to the welding temperature of 1150℃ at a rate of 10℃ / min; in the fifth stage, the temperature is kept warm at the welding temperature of 1150℃ for 45 minutes, a pressure of 0.03MPa is applied, and then the furnace is cooled to room temperature; the vacuum degree of the vacuum brazing furnace is 200℃. .

[0026] The high entropy alloy brazing filler metal prepared by the present invention is used for brazing nickel-based powder high-temperature alloys. The specific effect of the high entropy alloy brazing filler metal on the mother material nickel-based powder high-temperature alloy is as follows: Co in the high entropy alloy brazing filler metal of the present invention replaces part of Ni in the traditional nickel-based brazing filler metal, and while forming an infinite solid solution with Ni, it can reduce the solubility of elements such as Al and Ti in the matrix, increase the amount of strengthening phase, and thus improve the overall performance of the alloy, wherein the concentrations of Co and Cr elements are similar to those of the mother material, have good compatibility, and are more conducive to the formation of stable and uniform joints; Mo can maintain the thermal strength of the brazing filler metal on the one hand, and refine the grains and reduce the cost on the other hand. In addition, compared with W, its melting point is lower, which is more conducive to the melting of the brazing filler metal; Ge and Ga replace the melting-reducing elements B and Si added in the traditional brazing filler metal. While reducing the melting point, Ge itself has a certain affinity for oxygen and will preferentially combine with oxygen at high temperature, thereby improving the oxidation resistance of the joint; Ga can partially replace Al, adjust γ The lattice mismatch of the γ' phase improves its stability and strengthening effect; Zr and Hf are elements that strongly form the γ' phase. Zr tends to segregate at grain boundaries, filling vacancies and enhancing grain boundary strength. Hf has a high melting point, which can promote the dispersion of carbides while improving the thermal strength of the joint, thereby improving the stability of grain boundaries and carbides; Pd can improve the wettability of the brazing filler metal on the parent material and has excellent oxidation and corrosion resistance at high temperatures. Pd can also form a solid solution with Ni, enhancing the mechanical properties of the joint; trace addition of Mg helps to improve the toughness of the brazed joint and can preferentially react with oxygen at high temperatures to exhibit oxidation resistance; Os atoms can dissolve into the nickel matrix, hindering dislocation movement through lattice distortion, and also promote the formation of dense Cr and Al oxide films, improving the oxidation resistance of the joint at high temperatures; the combined action of Ce and La refines the grains, and at the same time produces a composite microalloying effect with elements such as Zr and Ti, reducing the crack tendency and contributing to the improvement of creep properties.

[0027] In the present invention, the base material nickel-based powder high-temperature alloy can be selected from one or more of FGH99 nickel-based high-temperature alloy, FGH95 nickel-based high-temperature alloy, FGH96 nickel-based high-temperature alloy, FGH97 nickel-based high-temperature alloy, and FGH98 nickel-based high-temperature alloy.

[0028] The present invention will be further described below with reference to specific examples.

[0029] Example 1 This embodiment uses a high-entropy alloy brazing filler metal with an atomic ratio of Co 20%, Cr 15%, Al 8%, Mo 4%, Hf 5%, Zr 4%, Ge 3%, Ga1%, Ti 3%, Pd 3%, Os 0.5%, Mg 0.15%, Ce 0.05%, La 0.03%, and the balance being Ni. The base material is FGH99 nickel-based high-temperature alloy. The specific process is as follows: Step 1: Weigh pure metal element particles Co, Cr, Al, Mo, Hf, Zr, Ge, Ga, Ti, Pd, Os, Mg, Ce, and La according to the atomic ratio of the constituent elements of the above-mentioned high-entropy alloy solder. Then, clean the surface of the metal particles with a 5wt.% NaHCO3 solution to remove oil and impurities, rinse with deionized water, and finally clean the surface with anhydrous ethanol and place in a drying oven. Dry at 150°C for 90 minutes, place the cleaned metal particles in a vacuum planetary mixer according to the required atomic ratio, and mix them in stages for 2 hours to obtain a mixed powder; Step 2: Place the obtained mixed powder in a tungsten crucible and use vacuum arc melting method. The vacuum degree should be maintained at The alloy was then smelted three times with electromagnetic stirring, and then vacuum-cooled in the furnace to obtain a high-entropy alloy ingot. Step 3, the high entropy alloy ingot is first subjected to multiple hot rolling, with a single pass reduction rate of 8%, and then the high entropy alloy ingot obtained after hot rolling is cut into a flat cuboid such as 30mm×30mm×5mm by an electric spark wire cutting machine, and then it is subjected to multiple cold rolling to obtain a cold-rolled sheet with a thickness of 100μm, and then the cold-rolled sheet is segmented by the electric spark wire cutting machine and polished to a thickness of 50μm with a high-speed precision transverse thinning grinder, and the thickness error is controlled within ±3μm, and then the polished sheet is mechanically polished with a silica polishing liquid with a particle size of 150nm. After polishing, it is ultrasonically cleaned with anhydrous ethanol for 15min and dried in an inert gas protection dryer for 15min. After drying, it is taken out in time to obtain a high entropy alloy solder; Step 4: The base material FGH99 nickel-based high-temperature alloy is ground and polished in sequence using sandpaper with mesh sizes of 160#, 240#, 400#, 600#, 800#, 1000#, 1500#, and 2000# and a silica polishing liquid with a particle size of 150nm; after the grinding and polishing treatment is completed, the base material nickel-based powder high-temperature alloy is ultrasonically cleaned in anhydrous ethanol for 15 minutes, then rinsed with deionized water, and finally cleaned with anhydrous ethanol and placed in a drying oven, and dried at 150°C for 20 minutes to obtain the pretreated base material; then, the prepared high-entropy alloy brazing filler metal is placed between the upper and lower layers of nickel-based powder high-temperature alloy, and then placed in a vacuum brazing furnace for brazing; The specific process of brazing is as follows: in the first stage, the vacuum brazing furnace is heated from room temperature to 300℃ at a rate of 10℃ / min and kept warm for 10 minutes; in the second stage, the temperature is increased from 300℃ to 700℃ at a rate of 10℃ / min and kept warm for 10 minutes; in the third stage, the temperature is increased from 700℃ to 900℃ at a rate of 10℃ / min and kept warm for 10 minutes; in the fourth stage, the temperature is increased from 900℃ to the welding temperature of 1150℃ at a rate of 10℃ / min; in the fifth stage, the temperature is kept warm at the welding temperature of 1150℃ for 45 minutes, a pressure of 0.03MPa is applied, and then the furnace is cooled to room temperature; the vacuum degree of the vacuum brazing furnace is 200℃. .

[0030] The SEM micromorphology of the joint obtained by brazing FGH99 nickel-based high-temperature alloy using the high-entropy alloy brazing material prepared in this embodiment is as follows: Figure 1 As shown, the elements in the joint are uniformly diffused, and the borides are small and dispersed, which helps improve the joint's resistance to crack growth and thus enhance its mechanical properties. Mechanical testing of the joint using an INSTRON 3382 electronic universal testing machine revealed a shear strength of 804 MPa.

[0031] Example 2 In this embodiment, a high-entropy alloy solder with an atomic ratio of Co 20%, Cr 15%, Al 8%, Mo 4%, Hf 5%, Zr 4%, Ge 3%, Ga1%, Ti 3%, Pd 3%, Os 0.5%, Mg 0.15%, Ce 0.05%, and La 0.03%, with the balance being Ni, and the parent material is FGH99 nickel-based high-temperature alloy. The prepared high-entropy alloy solder has a thickness of 60 μm, and the remaining steps are the same as in Example 1. The mechanical properties of the joint are tested using an INSTRON 3382 electronic universal material testing machine, and it is found that the shear strength reaches 783 MPa.

[0032] Example 3 In this embodiment, a high-entropy alloy solder with an atomic ratio of Co 20%, Cr 15%, Al 8%, Mo 4%, Hf 5%, Zr 4%, Ge 3%, Ga1%, Ti 3%, Pd 3%, Os 0.5%, Mg 0.15%, Ce 0.05%, and La 0.03%, with the balance being Ni, and the parent material is FGH99 nickel-based high-temperature alloy. The thickness of the prepared high-entropy alloy solder is 80 μm, and the remaining steps are the same as in Example 1. The mechanical properties of the joint are tested using an INSTRON 3382 electronic universal material testing machine, and it is found that the shear strength reaches 737 MPa.

[0033] Example 4 In this embodiment, a high-entropy alloy brazing filler metal with an atomic ratio of Co 20%, Cr 15%, Al 8%, Mo 4%, Hf 5%, Zr 4%, Ge 3%, Ga1%, Ti 3%, Pd 3%, Os 0.5%, Mg 0.15%, Ce 0.05%, and La 0.03%, with the balance being Ni, is used to perform heterogeneous brazing of FGH99 nickel-based superalloy and FGH97 nickel-based superalloy. The thickness of the prepared high-entropy alloy brazing filler metal is 40 μm, and the remaining steps are the same as those in Example 1. The mechanical properties of the joint are tested using an INSTRON 3382 electronic universal material testing machine, and it is found that the shear strength reaches 812 MPa.

[0034] Example 5 In this embodiment, a high-entropy alloy brazing filler metal having an atomic ratio of Co 20%, Cr 15%, Al 8%, Mo 4%, Hf 5%, Zr 4%, Ge 3%, Ga1%, Ti 3%, Pd 3%, Os 0.5%, Mg 0.15%, Ce 0.05%, and La 0.03%, with the balance being Ni, is used to perform heterogeneous brazing of FGH99 nickel-based superalloy and FGH95 nickel-based superalloy. The thickness of the prepared high-entropy alloy brazing filler metal is 40 μm, and the remaining steps are the same as those in Example 1. The mechanical properties of the joint are tested using an INSTRON 3382 electronic universal material testing machine, and it is found that the shear strength reaches 746 MPa.

[0035] Comparative Example 1 In this comparative example, a brazing material with an atomic ratio of Co 15%, Cr 10%, Si 5%, B 3%, Fe 2% and the balance Ni was used to braze FGH99 nickel-based high-temperature alloy. The remaining steps were the same as those in Example 1. The SEM micromorphology of the joint obtained after brazing is as follows: Figure 2 As shown, there are bright white brittle phases on both sides, which are Figure 1 contrast, Figure 1 The joint interface is straighter, with fewer defects such as holes, and the element distribution is more uniform; the mechanical properties of the joint of this comparative example are tested using an INSTRON3382 electronic universal material testing machine, and it is found that the shear strength is 584 MPa. Compared with Example 1, the mechanical properties of the joint are greatly reduced.

[0036] Comparative Example 2 In this comparative example, a high entropy alloy brazing material with an atomic ratio of Co 20%, Cr 15%, Al 8%, W 4%, Ti 3%, Pd 3%, Os 0.5%, Mg 0.15%, Ce 0.05%, and La 0.03%, with the balance being Ni, was used to braze FGH99 nickel-based high-temperature alloy. The remaining steps were the same as those in Example 1. The SEM micromorphology of the joint obtained after brazing is shown in FIG. Figure 3 As shown, the joint was tested for mechanical properties using an INSTRON 3382 electronic universal material testing machine, and it was found that the shear strength reached 466 MPa; Compared with Example 1, the solder of this comparative example selects W with a higher melting point as an element to maintain thermal strength, and does not contain Hf, Zr, Ge, and Ga, which are elements with a melting-depressing effect in the high entropy alloy solder provided by the present invention. Figure 3 It can be seen that there are large pieces of white tungsten-containing brittle phases in the center area of ​​the joint. At the same time, due to the use of high-melting-point element W to enhance the thermal strength of the solder, the solder does not fully react with the base material during the brazing process, forming a large number of gray heterogeneous brittle crystals. In addition, the morphology of the central area is also quite different from that of the base material, and segregation is serious. Compared with Example 1, the mechanical properties of the joint are greatly reduced.

[0037] The above embodiments are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions or replacements made by those skilled in the art based on the technical features of the present invention fall within the scope of protection of the present invention.

Claims

1. A high entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys, characterized in that: The high entropy alloy solder is composed of the following elements in the following atomic ratio: Co 15-20%, Cr 15-18%, Al 5-8%, Mo 4-7%, Hf+Zr 8-10%, Ge+Ga 3-5%, Ti 2-3%, Pd 2-5%, Os 0.5%, Mg 0.15%, Ce 0.05%, La 0.03%, and the balance is Ni, and the element purity is greater than 99.99wt.%.

2. A method for preparing a high entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys according to claim 1, characterized in that: The preparation method of the high entropy alloy solder is: Step 1: Weigh pure metal element particles Co, Cr, Al, Mo, Hf, Zr, Ge, Ga, Ti, Pd, Os, Mg, Ce, and La according to the atomic ratio of the constituent elements of the high-entropy alloy solder, wash and dry them, place them in a vacuum planetary mixer, and mix them in stages for 2 hours to obtain a mixed powder; Step 2: placing the mixed powder in a tungsten crucible and preparing a high entropy alloy ingot by vacuum arc melting; Step 3: The high entropy alloy ingot is subjected to multiple hot rolling and multiple cold rolling to obtain a cold-rolled sheet, which is cut into sections and then polished using a grinder to obtain a target intermediate layer, and then polished, cleaned, and dried to obtain the high entropy alloy brazing material.

3. The method for preparing a high entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys according to claim 2, characterized in that: The staged mixing in step 1 includes: The first stage is pre-mixing, mixing at 20%-30% of the revolution speed for 15 minutes; The second stage, main mixing, is mixing at 70%-80% of the revolution speed for 90 minutes; The third stage is stable mixing, mixing at 20%-30% of the revolution speed for 15 minutes to obtain the mixed powder.

4. The method for preparing a high entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys according to claim 2, characterized in that: In the process of preparing high entropy alloy ingot by vacuum arc melting method in step 2, the vacuum degree during melting is , smelting times>3 times.

5. The method for preparing a high entropy alloy brazing filler metal for nickel-based powder high-temperature alloy connection according to claim 2, characterized in that: The reduction rate of a single pass of the multi-pass hot rolling is 5%-8%, and the reduction rate of a single pass of the multi-pass cold rolling is 8%-11%; the thickness of the cold-rolled sheet is 100μm-200μm; the thickness of the target intermediate layer is 40μm-80μm, and the thickness error is ±3μm.

6. Use of the high entropy alloy brazing filler metal for connecting nickel-based powder high-temperature alloys according to claim 1 in brazing nickel-based powder high-temperature alloys, characterized in that: The high entropy alloy brazing material serves as an intermediate layer to connect the nickel-based powder high-temperature alloy.

7. Application of the high entropy alloy brazing filler metal according to claim 6 in brazing of nickel-based powder high-temperature alloys, characterized in that: The nickel-based powder high-temperature alloy is one or more of FGH99 nickel-based high-temperature alloy, FGH95 nickel-based high-temperature alloy, FGH96 nickel-based high-temperature alloy, FGH97 nickel-based high-temperature alloy, and FGH98 nickel-based high-temperature alloy.

8. Application of the high entropy alloy brazing filler metal according to claim 6 in brazing of nickel-based powder high-temperature alloys, characterized in that: In the process of connecting the nickel-based powder high-temperature alloy with the high-entropy alloy as an intermediate layer, the high-entropy alloy brazing material is placed between the upper and lower layers of nickel-based powder high-temperature alloy, and then placed in a vacuum brazing furnace for brazing.

9. Application of the high entropy alloy brazing filler metal according to claim 8 in brazing nickel-based powder high-temperature alloys, characterized in that: The brazing adopts a segmented heating and pressurizing method, and the specific process is as follows: in the first stage, the vacuum brazing furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept warm for 10 minutes; in the second stage, the temperature is increased from 300°C to 700°C at a rate of 10°C / min and kept warm for 10 minutes; in the third stage, the temperature is increased from 700°C to 900°C at a rate of 10°C / min and kept warm for 10 minutes; in the fourth stage, the temperature is increased from 900°C to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the temperature is kept at the welding temperature of 1150°C for 45 minutes, a pressure of 0.03MPa is applied, and then the furnace is cooled to room temperature; the vacuum degree of the vacuum brazing furnace is .

10. Use of the high entropy alloy brazing material according to claim 9 in brazing nickel-based powder high-temperature alloys, characterized in that: Before brazing in a vacuum brazing furnace, the nickel-based powder high-temperature alloy is ground and polished with sandpaper and polishing liquid, and then ultrasonically cleaned in anhydrous ethanol, rinsed with deionized water, and then cleaned with anhydrous ethanol and dried.

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