Method for brazing AlxCoCrFeNi high-entropy alloy with single foil and brazed joint prepared thereby

Abstract

The application provides a method for brazing AlxCoCrFeNi high-entropy alloy by using a single foil, and the method comprises the following steps: providing a single foil and two AlxCoCrFeNi high-entropy alloys, wherein 0 < x < 0.3, the single foil is composed of elements Nb and Ni, and the atomic ratio of Nb and Ni ranges from 100% to 95.3%; grinding the to-be-brazed parts of the two AlxCoCrFeNi high-entropy alloys respectively to obtain two to-be-brazed base materials; cleaning the to-be-brazed parts of the two to-be-brazed base materials and the single foil; stacking a to-be-brazed base material, the single foil and another to-be-brazed base material in sequence to form a to-be-brazed assembly, wherein the single foil is attached to the to-be-brazed parts of the corresponding to-be-brazed base materials on opposite sides; placing a pressing block on one side of the to-be-brazed assembly to compress the to-be-brazed assembly; and placing the compressed to-be-brazed assembly into a brazing furnace for brazing, and the heating temperature is 1280 DEG C to 1320 DEG C, and the holding time is 2 min to 360 min, so as to obtain a brazed joint. The application further provides a brazed joint, which has high connection strength, good radiation resistance and low-temperature resistance, and can be applied to the fields of aerospace, nuclear energy and other extreme service environments.

Description

Technical Field

[0001] This application relates to the field of welding technology, specifically to a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil and the brazed joint prepared therefrom. Background Technology

[0002] High-entropy alloys are novel alloy materials formed by introducing "chemical disorder" through the mixing of multiple principal elements. They have the characteristics of radiation resistance, extreme low temperature resistance, oxidation resistance, corrosion resistance, high temperature resistance, and good structural stability. As low-temperature resistant and radiation-resistant materials, they have great application value in nuclear energy, aerospace, and civilian fields. In the nuclear energy field, they can be used as materials for helium-cooled divertors.

[0003] AlxCoCrFeNi high-entropy alloy has a face-centered cubic crystal structure, exhibiting good radiation resistance and low-temperature toughness. It has been reported that AlxCoCrFeNi's radiation resistance is significantly superior to traditional nuclear energy materials such as M316 stainless steel, zirconium alloys, and nickel-based alloys. After thermodynamic processing, AlxCoCrFeNi fibers show tensile strengths of up to 1207 MPa / 7.8 at room temperature and 1600 MPa / 17.5% at low temperature, making it suitable for use in components resistant to extreme low temperatures.

[0004] Currently, limitations in equipment and processes make direct manufacturing of complex AlxCoCrFeNi high-entropy alloy structures difficult. Therefore, achieving reliable joining of AlxCoCrFeNi high-entropy alloys has significant application value. Because AlxCoCrFeNi high-entropy alloys have five components, ordinary fusion welding methods, such as MIG welding, laser welding, and electron beam welding, often involve complex physicochemical reactions at high temperatures, easily generating various intermetallic compound phases that weaken the joint strength. Furthermore, Al... X CoCrFeNi high-entropy alloys exhibit poor electrical and thermal conductivity, making them prone to hot cracking after traditional fusion welding. Traditional brazing with Ni-based filler metals such as BNi-2 and BNi-5 easily leads to the formation of borides and phosphides in the brazing seam and base metal. These brittle and hard phases reduce joint strength. Ti-based filler metals readily react with Al... X CoCrFeNi forms a brittle and hard phase, and traditional Ag-based, Ni-based, and Cu-based brazing fillers are prone to low-temperature brittle fracture after soldering, resulting in poor low-temperature service performance of the joint. Summary of the Invention

[0005] Therefore, this application provides a method for brazing AlxCoCrFeNi high-entropy alloy using single foil and the brazed joint prepared therefrom, in order to solve the technical problems of traditional fusion welding being prone to hot cracking after welding, and traditional brazing filler metal being prone to generating unfavorable brittle and hard phases and having poor low-temperature service performance.

[0006] This application proposes a method for brazing AlxCoCrFeNi high-entropy alloys using a single foil, comprising the following steps:

[0007] Provide a single foil and two AlxCoCrFeNi high-entropy alloys, wherein 0 < x < 0.3, the single foil being composed of elements Nb and Ni, the atomic ratio of Nb to Ni ranging from 100% to 95.3%;

[0008] The two areas of the AlxCoCrFeNi high-entropy alloy to be welded were ground separately to obtain two base materials to be welded;

[0009] Clean the welding areas of the two base materials to be welded and the single foil;

[0010] A base material to be welded, a single foil, and another base material to be welded are sequentially stacked to form a welding assembly, wherein the opposite sides of the single foil are attached to the corresponding welding portions of the base material to be welded;

[0011] A pressure block is placed on one side of the component to be welded to press the component firmly.

[0012] The compressed component to be brazed is placed in a brazing furnace for brazing. The temperature is raised to 1280℃-1320℃ and the holding time is 2min-360min to obtain a brazed joint.

[0013] In some embodiments, the step of grinding the two weldable portions of the AlxCoCrFeNi high-entropy alloy to obtain two base materials for welding specifically includes:

[0014] The areas of the AlxCoCrFeNi high-entropy alloy to be welded were successively polished using 400-grit, 800-grit, 1200-grit, and 2000-grit sandpaper.

[0015] In some embodiments, the thickness of the single foil ranges from 10 μm to 100 μm.

[0016] In some embodiments, the step of cleaning the welding areas of the two base materials to be welded and the single foil specifically includes:

[0017] The base material to be welded and the single foil are immersed in acetone solution, cleaned by ultrasonic cleaning for 10-30 minutes, and then dried.

[0018] The dried base material and the single foil are immersed in an ethanol solution, cleaned with ultrasound for 10-20 minutes, and then dried.

[0019] In some embodiments, the pressure applied by the pressure block to the component to be welded is 0.05N-0.5N.

[0020] In some embodiments, during brazing in the brazing furnace, the furnace chamber is evacuated to a vacuum level of 2 × 10⁻⁶. -3 Pa-5.0×10 -3 Pa.

[0021] In some embodiments, prior to the brazing, the heating rate of the component to be brazed is 5°C / min to 20°C / min.

[0022] In some embodiments, after the brazing, the cooling rate of the welded component is 5°C / min-10°C / min.

[0023] In some embodiments, during the brazing process, the component to be brazed is heated to 1280°C and held at that temperature for 10 minutes.

[0024] This application also proposes a brazed joint, characterized in that it comprises a single foil and two AlxCoCrFeNi high-entropy alloys, wherein the single foil is connected between the two AlxCoCrFeNi high-entropy alloys, wherein 0 < x < 0.3, and the single foil is composed of elements Nb and Ni, with the Nb to Ni atomic ratio ranging from 100% to 95.3%.

[0025] In the brazed joints prepared by the above method, since 0 < x < 0.3, the Nb to Ni atomic ratio in the single foil ranges from 100% to 95.3%. After the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, a reaction eutectic reaction is formed to generate a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. FCC has radiation resistance and low-temperature resistance. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. The obtained brazed joint interface composition is also good. The brazed joint is uniform and crack-free, with no other brittle and hard phases generated. It has high brazing strength and good resistance to radiation and low temperature. It can be used in extreme service environments such as aerospace and nuclear energy. When x is greater than or equal to 0.3, the high-entropy alloy has a face-centered cubic and body-centered cubic two-phase structure. The high-entropy alloy has a high Al content. After dissolving into a Ni-Nb liquid phase, Al is easily reacted with Ni in the Ni foil during the cooling process, forming a brittle and hard B2 phase structure in the brazing seam. This easily generates microcracks and weakens the mechanical properties of the joint. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of the brazed joint proposed in this application.

[0027] Figure 2 This is a backscattered photograph of the brazed joint proposed in this application.

[0028] Figure 3 This is the shear fracture morphology of the brazed joint proposed in this application.

[0029] Figure 4 This is a flowchart of the method for brazing AlxCoCrFeNi high-entropy alloy using a single foil, as proposed in this application.

[0030] Figure 5 for Figure 4 The flowchart illustrates the steps of cleaning the two base materials to be welded, the areas to be welded, and the single foil. Detailed Implementation

[0031] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0032] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0035] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0036] Please see Figures 1 to 3 This application proposes a brazed joint 100, comprising a single foil 10 and two AlxCoCrFeNi high-entropy alloys 20, wherein 0 < x < 0.3, and the single foil is composed of elements Nb and Ni, with the Nb to Ni atomic ratio ranging from 100% to 95.3%.

[0037] A single foil 10 is placed between two AlxCoCrFeNi high-entropy alloys 20. Each AlxCoCrFeNi high-entropy alloy 20 has a welding part. The two opposite sides of the single foil 10 are connected to the welding parts of the two AlxCoCrFeNi high-entropy alloys 20 by brazing.

[0038] In some embodiments, the thickness of the single foil 10 ranges from 10 μm to 100 μm. In this way, the single foil 10 and the AlxCoCrFeNi high-entropy alloy 20 can more easily undergo a eutectic reaction, and the intermediate layer reaction is complete. When the thickness of the single foil 10 is less than 10 μm, the surface flatness and roughness requirements of the AlxCoCrFeNi high-entropy alloy are high, and incomplete welding is likely to occur after welding. When the thickness of the single foil 10 is greater than 100 μm, some single foils will not react completely, and the joint is prone to brittle fracture.

[0039] In the aforementioned brazed joints, since 0 < x < 0.3, the Nb to Ni atomic ratio in the single foil ranges from 100% to 95.3%. After the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy 20, a reaction eutectic reaction occurs, forming a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. The FCC phase exhibits radiation resistance and low-temperature resistance. When the joint is under stress after welding, the alternating slippage of the FCC and Laves phases enhances the mechanical properties of the joint. Furthermore, the obtained brazed joint interface structure... The high-entropy alloy exhibits uniformity and is free of cracks, with no other brittle or hard phases. It boasts high brazed joint strength and good resistance to radiation and low temperatures, making it suitable for applications in extreme service environments such as aerospace and nuclear energy. When x is greater than or equal to 0.3, the high-entropy alloy has a face-centered cubic and body-centered cubic two-phase structure. The high-entropy alloy contains a relatively high Al content. After dissolving into a Ni-Nb liquid phase, Al readily reacts with Ni in the Ni foil during cooling, forming a brittle and hard B2 phase structure in the brazed joint. This structure is prone to microcracks, weakening the mechanical properties of the joint.

[0040] Please see Figure 4 This application also proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil, comprising the following steps:

[0041] S10 provides a single foil and two AlxCoCrFeNi high-entropy alloys, wherein 0 < x < 0.3, the single foil is composed of Nb and Ni, and the atomic ratio of Nb to Ni ranges from 100% to 95.3%.

[0042] Thus, the single foil is only a face-centered cubic phase, which has good plasticity and can make good contact with the AlxCoCrFeNi high-entropy alloy during brazing, and is easy to undergo eutectic reaction. However, when the Nb and Ni atomic ratio content is less than 95.3%, the single foil is prone to forming the Nb7Ni6 brittle and hard phase, which has poor plasticity and is not conducive to eutectic reaction with the AlxCoCrFeNi high-entropy alloy.

[0043] The thickness of the single foil ranges from 10μm to 100μm. This allows for a more eutectic reaction between the single foil and the AlxCoCrFeNi high-entropy alloy, and ensures complete reaction of the intermediate layer. When the thickness of the single foil is less than 10μm, the surface smoothness and roughness of the AlxCoCrFeNi high-entropy alloy are required to be high, and incomplete welding is likely to occur after soldering. When the thickness of the single foil is greater than 100μm, some single foils may not react completely, and the joint may easily break.

[0044] S20, grind the two AlxCoCrFeNi high-entropy alloy parts to be welded to obtain two base materials to be welded;

[0045] The welding areas of the AlxCoCrFeNi high-entropy alloy were successively polished using 400-grit, 800-grit, 1200-grit, and 2000-grit sandpaper. It is understood that the sandpaper may include, but is not limited to, SiC sandpaper, as well as wood sandpaper and wet sandpaper.

[0046] S30, clean the welding areas and single foils of the two base materials to be welded;

[0047] In some embodiments, see Figure 5 The cleaning steps specifically include:

[0048] S31, Immerse the base material and single foil to be welded in acetone solution, clean them with ultrasonic cleaning for 10-30 minutes and then dry them;

[0049] After cleaning, the surface of the base material to be welded is clean and free of oil stains and other contaminants.

[0050] S32, immerse the dried base material and single foil into an ethanol solution, clean them with ultrasound for 10-20 minutes and then dry them.

[0051] After cleaning, no other substances remain on the surface. Acetone is mainly used to remove any oil stains or other contaminants that may be present on the surface, while alcohol is used to remove any impurities or contaminants that may be present on the surface.

[0052] S40, a base material to be welded, a single foil and another base material to be welded are stacked in sequence to form a component to be welded, wherein the opposite sides of the single foil are attached to the corresponding welding parts of the base material to be welded;

[0053] S50, Place a pressure block on one side of the component to be welded to press the component firmly;

[0054] The compressed block includes, but is not limited to, a graphite compressed block.

[0055] In some embodiments, the pressure applied by the pressure block to the assembly to be welded is 0.05N-0.5N. When the applied pressure is within this range, the AlxCoCrFeNi high-entropy alloy base material and the single foil are in full contact, making it easier for a eutectic reaction to occur, resulting in a beautiful interface structure and good joint performance after welding. When the applied pressure is less than 0.05N, the AlxCoCrFeNi high-entropy alloy base material and the single foil are not in sufficient contact, resulting in a small interface contact area after welding and low joint strength. When the applied pressure is greater than 0.5N, the excessive pressure makes it easy for the generated filling liquid phase to be squeezed out of the brazing seam, resulting in more Laves brittle hard phase in the joint and reducing the joint strength.

[0056] S60, the compressed components to be brazed are placed in a brazing furnace for brazing, the temperature is heated to 1280℃-1320℃, and the holding time is 2min-360min, to obtain the brazed joint.

[0057] Specifically, when the heating temperature is between 1280℃ and 1320℃, the single foil can undergo a complete eutectic reaction with the AlxCoCrFeNi high-entropy alloy base material, generating a liquid phase that fully fills the brazing seam, resulting in a high bonding strength between the brazing seam and the base material. When the heating temperature is below 1280℃, the single foil cannot undergo a eutectic reaction with the AlxCoCrFeNi high-entropy alloy base material to generate a liquid phase, resulting in a brittle and hard phase structure with cracks at the joint and low joint strength. When the heating temperature is above 1320℃, a brittle and hard B2 phase will precipitate at the interface and penetrating cracks will appear, resulting in low joint strength.

[0058] In this embodiment, during brazing, the component to be brazed is heated to 1280°C and held at that temperature for 10 minutes.

[0059] In some embodiments, when brazing is performed in a brazing furnace, the furnace chamber is evacuated to a vacuum level of at least 5.0 × 10⁻⁶. -3 Pa, the resulting eutectic liquid phase has good fluidity, effectively fills the braze seam, produces a uniform microstructure after welding, and has a high welding success rate. When the furnace cavity is evacuated to a vacuum greater than 5.0 × 10⁻⁶, -3 When Pa is reached, the single foil cannot react with the AlxCoCrFeNi high-entropy alloy base material. The AlxCoCrFeNi high-entropy alloy base material is easily oxidized during the heating process, which is not conducive to the eutectic reaction between the single foil and the AlxCoCrFeNi high-entropy alloy. The resulting filled liquid phase has poor fluidity.

[0060] In some embodiments, before brazing, the heating rate of the components to be brazed is 5℃ / min-20℃ / min. This allows for better and more accurate control of the furnace temperature, resulting in a high joint strength after the brazing seam is filled. If the heating rate is less than 5℃ / min, the welding time is too long and energy is consumed. If the heating rate is greater than 20℃ / min, the furnace temperature is uneven and the welding quality is poor.

[0061] After brazing, if the cooling rate of the welded components is greater than 5°C / min, unfavorable intermetallic compounds are less likely to precipitate in the base material and brazing seam after welding. When the cooling rate is less than 5°C / min, unfavorable second-phase intermetallic compounds are more likely to precipitate in the base material and brazing seam after welding.

[0062] In the brazed joint prepared by the above method, after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, a reaction eutectic reaction is formed to generate a face-centered cubic (FCC) matrix and a layered eutectic structure of Laves phase. FCC has radiation resistance and low-temperature resistance. When the joint is under stress after welding, the FCC phase and Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint has a uniform interface structure without cracks and no other brittle hard phases are generated. The brazed joint has high connection strength and good radiation resistance and low-temperature resistance, and can be applied in extreme service environments such as aerospace and nuclear energy.

[0063] Furthermore, using a single foil as the intermediate layer in contact reaction brazing, it is difficult for the single foil and the AlxCoCrFeNi high-entropy alloy to achieve mutual diffusion and metallurgical bonding during the heating process. Only when the temperature reaches 1280℃ do they undergo a pseudo-binary eutectic reaction, producing a liquid phase. The single foil gradually melts, and when it is completely melted, the base material dissolves and diffuses into the molten liquid phase. By controlling the process parameters (continuously increasing the temperature or extending the holding time), the aggregation and growth of the brittle phase are controlled. Therefore, after cooling, a lamellar eutectic structure composed of a face-centered cubic matrix (FCC phase) and a Laves phase is formed at the interface, resulting in good metallurgical bonding. Although the Laves brittle phase is generated in the weld, it is distributed evenly and intermittently in the brazed seam, resulting in good joint performance. Compared with the prior art, the connection method of this application is simple, economical, and applicable. The obtained AlxCoCrFeNi high-entropy alloy brazed joint has an average room temperature shear strength of not less than 435 MPa and a liquid nitrogen temperature (77K) shear strength of 908 MPa, which has great potential for widespread application.

[0064] The technical solutions of this application are not limited to the specific embodiments exemplified below, but also include any combination of the specific embodiments.

[0065] Example 1

[0066] Embodiment 1 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil, comprising the following steps:

[0067] Provide a single foil and two AlxCoCrFeNi high-entropy alloys, where x = 0.28, the thickness of the single foil is 30 mm, and the single foil is composed of elements Nb and Ni with an atomic ratio of 100%.

[0068] The welding parts of the AlxCoCrFeNi high-entropy alloy were polished sequentially using sandpaper of 400 grit, 800 grit, 1200 grit and 2000 grit to obtain two base materials for welding.

[0069] The base material and single foil to be welded were immersed in acetone solution, ultrasonically cleaned for 20 minutes and then dried; then the dried base material and single foil were immersed in ethanol solution, ultrasonically cleaned for 15 minutes and then dried.

[0070] A base material to be welded, a single foil, and another base material to be welded are stacked in sequence to form a welding assembly. A pressure block is placed on one side of the welding assembly. The pressure block applies a pressure of 0.25N to the welding assembly to press the welding parts of the two base materials and the single foil together. The opposite sides of the single foil are attached to the corresponding welding parts of the base materials to be welded.

[0071] The compressed components to be brazed are placed in a vacuum brazing furnace for brazing at a vacuum degree of 3×10⁻⁶.-3 The brazed joint was obtained by heating to 1300℃ in an ambient temperature of 180°C / min at a rate of 10℃ / min and holding for 10min. After brazing, the joint was cooled to room temperature at a rate of 8℃ / min.

[0072] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint has a uniform interface structure without cracks and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of not less than 435 MPa and a liquid nitrogen temperature (77 K) shear strength of 908 MPa.

[0073] Example 2

[0074] Embodiment 2 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Embodiment 2 of this application is largely the same as Embodiment 1, except that:

[0075] In Example 2, the single foil is composed of elements Nb and Ni, with an atomic ratio of Nb to Ni of 99.5%.

[0076] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint interface structure is uniform and crack-free, and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 404 MPa and a liquid nitrogen temperature (77 K) shear strength of 902 MPa.

[0077] Example 3

[0078] Example 3 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Example 3 of this application is largely the same as Example 1, except that:

[0079] In Example 3, the single foil is composed of elements Nb and Ni, with an atomic ratio of Nb to Ni of 95.3%.

[0080] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint interface structure is uniform and crack-free, and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 403 MPa and a liquid nitrogen temperature (77 K) shear strength of 903 MPa.

[0081] Example 4

[0082] Example 4 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Example 4 of this application is largely the same as Example 1, except that:

[0083] In the AlxCoCrFeNi high-entropy alloy base material of Example 4, x = 0.1. It is understood that in other embodiments, x may also be 0.01, 0.02, 0.15, 0.18, 0.2, 0.21, 0.25, or 0.29, but is not limited thereto. It can be set according to actual needs. As long as it is in the range of 0 < x < 0.3, it is within the protection scope of this application.

[0084] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint has a uniform interface structure without cracks and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 405 MPa and a liquid nitrogen temperature (77 K) shear strength of 900 MPa.

[0085] Example 5

[0086] Example 5 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Example 5 of this application is largely the same as Example 1, except that:

[0087] In Example 5, the base material and single foil to be welded were immersed in an acetone solution, cleaned with ultrasound for 10 minutes, and then dried; then the dried base material and single foil were immersed in an ethanol solution, cleaned with ultrasound for 10 minutes, and then dried.

[0088] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint interface structure is uniform and crack-free, and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 419 MPa and a liquid nitrogen temperature (77 K) shear strength of 898 MPa.

[0089] Example 6

[0090] Example 6 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Example 6 of this application is largely the same as Example 2, except that:

[0091] In Example 6, the pressure applied to the assembly to be welded by the pressure block is 0.5N.

[0092] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint has a uniform interface structure without cracks and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 456 MPa and a liquid nitrogen temperature (77 K) shear strength of 1020 MPa.

[0093] Example 7

[0094] Example 7 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Example 7 of this application is largely the same as Example 2, except that:

[0095] In Example 7, the heating temperature during brazing was 1280℃, the heating rate was set to 10℃ / min, the holding time was 2min, and the cooling rate to room temperature after brazing was 5℃ / min, resulting in a brazed joint.

[0096] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint interface structure is uniform and crack-free, and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 385 MPa and a liquid nitrogen temperature (77 K) shear strength of 882 MPa.

[0097] Example 8

[0098] Example 8 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Example 8 is largely the same as Example 2, except that:

[0099] In Example 8, the heating temperature during brazing was 1280℃, the heating rate was set to 20℃ / min, the holding time was 30min, and the cooling rate to room temperature after brazing was 10℃ / min, resulting in a brazed joint.

[0100] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint interface structure is uniform and crack-free, and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 456 MPa and a liquid nitrogen temperature (77 K) shear strength of 979 MPa.

[0101] Example 9

[0102] Example 9 of this application proposes a method for brazing AlxCoCrFeNi high-entropy alloy using a single foil. Example 9 is largely the same as Example 8, except that:

[0103] In Example 9, the heating temperature during brazing was 1300℃, the heating rate was set to 5℃ / min, the holding time was 20min, and the cooling rate to room temperature after brazing was 20℃ / min, resulting in a brazed joint.

[0104] The experimental results show that after the single foil comes into contact with the AlxCoCrFeNi high-entropy alloy, the reactive eutectic reaction generates a face-centered cubic (FCC) matrix and a layered Laves phase eutectic structure. When the joint is under stress after welding, the FCC phase and the Laves phase can alternately slide to improve the mechanical properties of the joint. Moreover, the obtained brazed joint has a uniform interface structure without cracks and no other brittle hard phases are generated. The brazed joint has high connection strength, with an average room temperature shear strength of 465 MPa and a liquid nitrogen temperature (77 K) shear strength of 998 MPa.

[0105] In summary, the brazed joints prepared by the above method have an average room temperature shear strength of 385-435 MPa and a liquid nitrogen temperature (77 K) shear strength of up to 979 MPa, which has great potential for widespread application.

[0106] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application.

Claims

1. A method for using single-foil brazing of Al x The method for producing CoCrFeNi high-entropy alloys is characterized by... Includes the following steps: Provide a single foil and two Al x CoCrFeNi high-entropy alloy, wherein 0 < x < 0.3, the single foil is composed of elements Nb and Ni, the atomic ratio of Nb to Ni ranges from 100% to 95.3%, and the thickness of the single foil ranges from 10 μm to 100 μm; Grind the two Al respectively x Two base materials were obtained from the area to be welded in the CoCrFeNi high-entropy alloy. Clean the welding areas of the two base materials to be welded and the single foil; A base material to be welded, a single foil, and another base material to be welded are sequentially stacked to form a welding assembly, wherein the opposite sides of the single foil are attached to the corresponding welding portions of the base material to be welded; A pressure block is placed on one side of the component to be welded to press the component firmly. The compressed component to be brazed is placed in a brazing furnace for brazing. The temperature is raised to 1280℃-1320℃ and the holding time is 2min-360min to obtain a brazed joint.

2. The method of using single-foil brazing Al as described in claim 1 x The method for producing CoCrFeNi high-entropy alloys is characterized by... The two Al were polished respectively. x The steps for obtaining two base materials for welding the CoCrFeNi high-entropy alloy at the welding site specifically include: The Al was successively sanded using 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper. x The areas of the CoCrFeNi high-entropy alloy to be welded are ground.

3. The method of using single-foil brazing Al as described in claim 1 x The method for producing CoCrFeNi high-entropy alloys is characterized by... The step of cleaning the welding areas of the two base materials to be welded and the single foil specifically includes: The base material to be welded and the single foil are immersed in acetone solution, cleaned by ultrasonic cleaning for 10-30 minutes, and then dried. The dried base material and the single foil are immersed in an ethanol solution, cleaned with ultrasound for 10-20 minutes, and then dried.

4. The method of using single-foil brazing Al as described in claim 1 x The method for producing CoCrFeNi high-entropy alloys is characterized by... The pressure applied by the pressure block to the component to be welded is 0.05N-0.5N.

5. The method of using single-foil brazing Al as described in claim 1 x The method for producing CoCrFeNi high-entropy alloys is characterized by... During brazing in the brazing furnace, the furnace chamber is evacuated to a vacuum level of 2 × 10⁻⁶. -3 Pa-5.0×10 -3 Pa.

6. The method of using single-foil brazing Al as described in claim 1 x The method for producing CoCrFeNi high-entropy alloys is characterized by... Prior to the brazing, the heating rate of the component to be brazed is 5℃ / min-20℃ / min.

7. The method of using single-foil brazing Al as described in claim 6 x The method for producing CoCrFeNi high-entropy alloys is characterized by... After the brazing, the cooling rate of the welded component is 5℃ / min-10℃ / min.

8. The method of using single-foil brazing Al as described in claim 7 x The method for producing CoCrFeNi high-entropy alloys is characterized by... During the brazing process, the component to be brazed is heated to 1280°C and held at that temperature for 10 minutes.

9. A brazed joint, characterized in that, Includes a single foil and two Al x CoCrFeNi high-entropy alloy, the single foil is connected to two Al x The high-entropy alloy is composed of CoCrFeNi, where 0 < x < 0.3, and the single foil is composed of elements Nb and Ni, with the Nb to Ni atomic ratio ranging from 100% to 95.3%.

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