Auptpdni-based bimodal heterojunction high-entropy alloy electric contact material and preparation method thereof

Abstract

The application discloses AuPtPdNi-based bimodal heterojunction high-entropy alloy electric contact material and a preparation method thereof, and belongs to the technical field of electric contact materials.The AuPtPdNi-based bimodal heterojunction high-entropy alloy electric contact material comprises Au, Pt, Pd and Ni in equal atomic proportions.A bimodal distribution of grains is introduced into the heterostructure through cold rolling and double-stage aging treatment, and a multistage organizational structure of soft and hard alternation is formed in the material, so that the ductility is significantly improved while the hardness of the material is maintained.In addition, the combination of cold rolling and double-stage aging treatment and the design of the multi-principal element alloy composition form phase interfaces with different energy band structures in the matrix, the built-in electric field generated at the hetero-interface can effectively reduce the carrier scattering probability, reduce the grain boundary barrier height and reduce the resistivity.Meanwhile, the coherent or incoherent interface in the heterostructure can be used as a fast transmission channel for carriers, so that the carrier mobility is improved, and the material still maintains excellent conductivity stability under high-frequency and large-current working conditions.

Description

Technical Field

[0001] This invention belongs to the field of electrical contact materials technology, specifically relating to an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material and its preparation method. Background Technology

[0002] Electrical contact materials are core functional components in switches, connectors, and electronic devices, and their performance directly determines the stability of power systems and the lifespan of electronic products. With the development of high-end fields such as aerospace and precision instruments, stringent requirements have been placed on electrical contact materials, demanding that they possess high hardness, high strength, low resistivity, and excellent resistance to arc erosion.

[0003] Currently, precious metal electrical contact materials are mainly silver-based, gold-based, and platinum-based. Although silver-based materials have excellent conductivity, they have low hardness, poor wear resistance, and are prone to sulfidation, making it difficult to meet the requirements for high reliability and long service life. While traditional gold-based and platinum-based alloys have good chemical stability, they generally suffer from low softening temperatures, insufficient resistance to welding, and are prone to material transfer under complex electric arc conditions.

[0004] In recent years, high-entropy alloys have exhibited excellent mechanical properties and thermal stability due to their unique high mixing entropy effect. However, current research on high-entropy alloys of noble metals is still insufficient and usually faces two major technical challenges: first, the melting points of noble metals vary greatly, making it difficult to achieve atomic-level homogeneous mixing through conventional smelting; second, while achieving high strength, the alloys often experience a decrease in plasticity, and traditional single-stage aging treatments tend to form discontinuous precipitates at grain boundaries, leading to intergranular brittle fracture during service.

[0005] Therefore, this paper proposes an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material and its preparation method. This approach aims to significantly improve the material's strength and ductility while retaining excellent conductivity, thus meeting the processing performance requirements of electrical contact materials in practical applications. Summary of the Invention

[0006] To address or partially address the problems existing in related technologies, this invention proposes an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material and its preparation method.

[0007] This invention provides an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material, comprising the following elements: Au, Pt, Pd, and Ni; wherein the atomic ratios of Au, Pt, Pd, and Ni are equal.

[0008] A method for preparing an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material includes the following steps: (1) Weigh Au, Pt, Pd and Ni elemental metals according to the equiatomic ratio, and mix the elemental raw materials to obtain a mixture; (2) The mixture is smelted in an inert atmosphere and then naturally cooled to obtain an ingot. (3) The ingot is cold rolled; (4) Perform a two-stage aging treatment on the material after cold rolling in step (3) to obtain AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material.

[0009] Preferably, the melting is vacuum arc melting, specifically including: first evacuating the vacuum to 5×10⁻⁶. -3 Below Pa, inert gas is added until the pressure is -0.05 MPa. The melting current is set to 400~500 A. The melting process involves multiple flipping and melting, and the melting time is 35~40 min.

[0010] Preferably, during the melting process, the surface is turned over no less than 8 times, and once every 3 to 4 minutes of melting.

[0011] Preferably, the melt is electromagnetically stirred during the smelting process, with a stirring current of 10~30A, to promote thorough mixing of elements, increase homogeneity, and reduce large-scale segregation.

[0012] Preferably, before the cold rolling process, the material is subjected to heat treatment at 900℃-1200℃ for 3-4 hours, followed by water quenching.

[0013] Preferably, during the cold rolling process, the total reduction is 40%, and the reduction per pass is 0.5%.

[0014] Preferably, in the two-stage aging treatment, the first stage aging treatment temperature is 400~600℃, the holding time is 2-4h, and after holding, it is cooled with the furnace or air-cooled; the second stage aging treatment temperature is 250~400℃, the holding time is 4-6h, and after holding, it is cooled with the furnace or air-cooled.

[0015] The technical solution provided by this invention has the following beneficial effects: This invention introduces a heterogeneous structure with a bimodal grain distribution through cold rolling and a two-stage aging process, forming a multi-level microstructure with alternating hard and soft layers within the material. This significantly improves ductility while maintaining material hardness. Furthermore, the combination of cold rolling and two-stage aging with a multi-principal element alloy composition design creates heterogeneous interfaces with different band structures within the matrix. On one hand, the introduced bimodal heterostructure promotes the accumulation of geometrically necessary dislocations, significantly enhancing the plastic processing capability of high-entropy alloys. On the other hand, the built-in electric field generated at the heterogeneous interface effectively reduces the carrier scattering probability and decreases the grain boundary barrier height, thereby significantly reducing resistivity. Simultaneously, the coherent or incoherent interfaces within the heterostructure serve as rapid carrier transport channels, increasing carrier mobility and enabling the material to maintain excellent conductivity stability under high-frequency and high-current operating conditions. Therefore, the method of this invention significantly improves the material's hardness and reduces its resistivity. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact materials.

[0017] Figure 2 The image shows the SEM-EDS image of the material prepared in Example 1.

[0018] Figure 3 This is a grain size distribution diagram of the material prepared in Example 1. Detailed Implementation

[0019] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate this invention.

[0020] Example 1 like Figure 1 A method for preparing an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material includes the following steps: (1) Weigh gold, platinum, palladium and nickel raw materials with a purity of 99.9% according to the atomic ratio (the corresponding mass fractions are 35.47%, 35.01%, 19.03% and 10.49%, respectively). Cut the metal raw materials into small gold, platinum, palladium and nickel particles with a size of not less than 5 mm, and mix them evenly by mechanical mixing to obtain the initial mixed raw materials.

[0021] (2) Place the initial mixed raw materials obtained in step (1) into a vacuum arc melting furnace. First, evacuate to 5×10 -3Below Pa, argon gas is introduced until the pressure reaches -0.05 MPa. The current is set to 400 A, and the electromagnetic stirring device of the melting furnace is started with a stirring current of 20 A to perform electric arc melting on the mixture. During the melting process, the mixture is flipped every 4 minutes, for a total of 8 flips. After melting for 35 minutes, the melt is removed and allowed to cool naturally to obtain button-shaped AuPtPdNi alloy ingots. (3) The alloy ingot obtained in step (2) is placed in an argon protective atmosphere furnace for homogenization heat treatment. The heat treatment temperature is 900℃ and the holding time is 3h, followed by water quenching.

[0022] (4) After the ingot has been processed, cold rolling operation is carried out to reduce its thickness from 10 mm to 6 mm. The total reduction is 40%, and the reduction per pass is 0.5%.

[0023] (5) The rolled sample is heated to 500°C, held for 2.5 hours and then cooled in the furnace or air-cooled. After that, it is heated to 300°C again, held for 5 hours and then air-cooled to room temperature to obtain AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material.

[0024] pass Figure 2 and Figure 3 As can be seen, the electrical contact material in Example 1 is a four-principal alloy composed of Au, Pd, Pt, and Ni, forming a bimodal heterostructure with fine recrystallized grains and unbroken large grains. The four-principal alloy electrical contact material prepared in this example has a Vickers hardness of 420 HV and a resistivity of 26.9 μΩ·cm.

[0025] Example 2 A method for preparing an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material includes the following steps: (1) Weigh gold, platinum, palladium and nickel raw materials with a purity of 99.9% according to the atomic ratio (the corresponding mass fractions are 35.47%, 35.01%, 19.03% and 10.49%, respectively). Cut the metal raw materials into small gold, platinum, palladium and nickel particles with a size of not less than 5 mm, and mix them evenly by mechanical mixing to obtain the initial mixed raw materials.

[0026] (2) Place the initial mixed raw materials obtained in step (1) into a vacuum arc melting furnace. First, evacuate to 5×10 -3Below Pa, argon gas was added until the pressure reached -0.05 MPa. The current was set to 400 A, and the electromagnetic stirring device of the melting furnace was started with a stirring current of 30 A to perform electric arc melting on the mixture. During the melting process, the mixture was flipped every 4 minutes, for a total of 9 flips. After melting for 36 minutes, the melt was removed and allowed to cool naturally to obtain button-shaped AuPtPdNi alloy ingots. (3) The alloy ingot obtained in step (2) is placed in an argon protective atmosphere furnace for homogenization heat treatment. The heat treatment temperature is 900℃ and the holding time is 3h, followed by water quenching.

[0027] (4) After the ingot has been processed, cold rolling operation is carried out to reduce its thickness from 10 mm to 6 mm. The total reduction is 40%, and the reduction per pass is 0.5%.

[0028] (5) The rolled sample is heated to 400°C, held for 3 hours and then cooled in the furnace or air-cooled. After that, it is heated to 400°C again, held for 6 hours and then air-cooled to room temperature to obtain AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material.

[0029] The four-principal-element alloy electrical contact material prepared in this embodiment has a Vickers hardness of 441 HV and a resistivity of 32.3 μΩ·cm.

[0030] Example 3 A method for preparing an AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material includes the following steps: (1) Weigh gold, platinum, palladium and nickel raw materials with a purity of 99.9% according to the atomic ratio (the corresponding mass fractions are 35.47%, 35.01%, 19.03% and 10.49%, respectively). Cut the metal raw materials into small gold, platinum, palladium and nickel particles with a size of not less than 5 mm, and mix them evenly by mechanical mixing to obtain the initial mixed raw materials.

[0031] (2) Place the initial mixed raw materials obtained in step (1) into a vacuum arc melting furnace. First, evacuate to 5×10 -3 Below Pa, argon gas was added until the pressure reached -0.05 MPa. The current was set to 500 A, and the electromagnetic stirring device of the melting furnace was started with a stirring current of 10 A to perform electric arc melting on the mixture. During the melting process, the mixture was flipped every 3 minutes, for a total of 13 flips. After melting for 39 minutes, the melt was removed and allowed to cool naturally to obtain button-shaped AuPtPdNi alloy ingots. (3) The alloy ingot obtained in step (2) is placed in an argon protective atmosphere furnace for homogenization heat treatment. The heat treatment temperature is 1200℃ and the holding time is 4h, followed by water quenching.

[0032] (4) After the ingot has been processed, cold rolling operation is carried out to reduce its thickness from 10 mm to 6 mm. The total reduction is 40%, and the reduction per pass is 0.5%.

[0033] (5) The rolled sample is heated to 600°C, held for 2 hours and then cooled in the furnace or air-cooled. After that, it is heated to 250°C again, held for 4 hours and then air-cooled to room temperature to obtain AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material.

[0034] The four-principal-element alloy electrical contact material prepared in this embodiment has a Vickers hardness of 397 HV and a resistivity of 24.6 μΩ·cm.

[0035] Comparative Example 1 A method for preparing an AuPdPtNi four-principal-element alloy electrical contact material includes the following steps: (1) Weigh gold, platinum, palladium and nickel raw materials with a purity of 99.9% according to the atomic ratio (the corresponding mass fractions are 35.47%, 35.01%, 19.03% and 10.49%, respectively). Cut the metal raw materials into small gold, platinum, palladium and nickel particles with a size of not less than 5 mm, and mix them evenly by mechanical mixing to obtain the initial mixed raw materials.

[0036] (2) Place the initial mixed raw materials obtained in step (1) into a vacuum arc melting furnace. First, evacuate to 5×10 -3 Below Pa, argon gas is then introduced until the pressure reaches -0.05 MPa. The current is set to 400 A, and the electromagnetic stirring device of the melting furnace is started to perform electric arc melting on the mixture. During the melting process, the mixture is flipped every 4 minutes, for a total of 8 flips. After melting for 35 minutes, the melt is removed and allowed to cool naturally to obtain button-shaped AuPtPdNi alloy ingots. (3) The alloy ingot obtained in step (2) is placed in an argon protective atmosphere furnace for homogenization heat treatment. The heat treatment temperature is 900℃, the holding time is 3h, and then it is water quenched.

[0037] (4) After the ingot has been processed, cold rolling operation is carried out to reduce its thickness from 10 mm to 6 mm. The total reduction is 40%, and the reduction per pass is 0.5%.

[0038] (5) Heat the rolled sample to 400°C, hold for 10 hours and then cool with the furnace or air to obtain AuPdPtNi four-principal alloy electrical contact material.

[0039] In this comparative example, single-stage aging only promotes matrix homogenization and cannot form a heterogeneous structure, and the mechanical and electrical properties show a significant decrease. The four-principal-element alloy electrical contact material prepared in this comparative example has a Vickers hardness of 191 HV and a resistivity of 110 μΩ·cm.

[0040] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material, characterized in that, It includes the following elements: Au, Pt, Pd, and Ni; wherein the atomic ratios of Au, Pt, Pd, and Ni are equal.

2. The method for preparing the AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material according to claim 1, characterized in that, Includes the following steps: (1) Weigh Au, Pt, Pd and Ni elemental metals according to the equiatomic ratio, and mix the elemental raw materials to obtain a mixture; (2) The mixture is smelted in an inert atmosphere and then naturally cooled to obtain an ingot. (3) The ingot is cold rolled; (4) Perform a two-stage aging treatment on the material after cold rolling in step (3) to obtain AuPtPdNi-based bimodal heterojunction high entropy alloy electrical contact material.

3. The method for preparing the AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material according to claim 1, characterized in that, The melting process is a vacuum arc melting process, specifically including: first, drawing a vacuum to 5×10... -3 Below Pa, inert gas is added until the pressure is -0.05 MPa. The melting current is set to 400~500 A. The melting process involves multiple flipping and melting, and the melting time is 35~40 min.

4. The method for preparing the AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material according to claim 1, characterized in that, During the smelting process, the surface is turned over no less than 8 times, and once every 3 to 4 minutes of smelting.

5. The method for preparing the AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material according to claim 1, characterized in that, During the smelting process, the melt is electromagnetically stirred with a stirring current of 10~30A.

6. The method for preparing the AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material according to claim 1, characterized in that, Before cold rolling, the material undergoes heat treatment at 900℃-1200℃ for 3-4 hours, followed by water quenching.

7. The method for preparing the AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material according to claim 1, characterized in that, During the cold rolling process, the total reduction is 40%, and the reduction per pass is 0.5%.

8. The method for preparing the AuPtPdNi-based bimodal heterojunction high-entropy alloy electrical contact material according to claim 1, characterized in that, In the two-stage aging treatment, the first stage aging treatment temperature is 400~600℃, the holding time is 2-4h, and after holding, it is cooled with the furnace or air-cooled; the second stage aging treatment temperature is 250~400℃, the holding time is 4-6h, and after holding, it is cooled with the furnace or air-cooled.

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