An Au-Pd-Ag-Pt-based multi-principal-element alloy electrical contact material and its preparation method

Abstract

This invention discloses an Au-Pd-Ag-Pt-based multi-principal-element alloy electrical contact material and its preparation method, belonging to the technical field of electrical contact materials. The multi-principal-element alloy electrical contact material of this invention comprises Au, Pd, Ag, and Pt, wherein the atomic ratios of Au, Pd, Ag, and Pt are equal. The preparation method includes mixing, melting, solution treatment, and two-stage aging treatment. By optimizing the alloy composition ratio and combining it with the corresponding preparation method, this invention successfully obtains an alloy electrical contact material that combines high mixing entropy effect, lattice distortion effect, and "cocktail" effect. This synergistically forms a stable FCC solid solution structure within the alloy, improving the overall performance of the alloy material, including hardness, strength, wear resistance, and corrosion resistance, thus meeting the comprehensive performance requirements of electrical contact materials in practical applications.

Description

Technical Field

[0001] This invention belongs to the field of electrical contact materials technology, and relates to an Au-Pd-Ag-Pt based multi-principal-element alloy electrical contact material and its preparation method. Background Technology

[0002] Electrical contact materials are key materials used to transmit current in electrical equipment. They are widely used in devices such as relays, switches, and sensors. Electrical contact materials are the core carrier for electrical appliances to realize the "connection-transmission-disconnection" of current and signal transmission, and their performance directly affects the reliability of electrical and electronic engineering.

[0003] With the rapid pace of technological advancements in electrical equipment, especially in critical fields such as national defense, aerospace, and precision instruments where material reliability and stability are paramount, ideal electrical contact materials must possess not only superior conductivity but also excellent wear resistance, high-temperature resistance, arc erosion resistance, and mechanical properties such as hardness and strength. However, existing electrical contact materials cannot achieve a comprehensive balance across conductivity, wear resistance, high-temperature resistance, and mechanical properties. For example, silver-based alloy electrical contact materials exhibit excellent conductivity, but their lower hardness, strength, and wear resistance significantly limit their practical applications.

[0004] Therefore, it is necessary to provide an Au-Pd-Ag-Pt-based multi-principal-element alloy electrical contact material and its preparation method, which can effectively improve the hardness, strength and other mechanical properties of the electrical contact material, as well as its wear resistance, high-temperature resistance and environmental tolerance, while maintaining the excellent conductivity of the electrical contact material, so as to meet the requirements of practical applications for the comprehensive performance of electrical contact materials. Summary of the Invention

[0005] To overcome the problems in the prior art, this invention optimizes the alloy composition and combines it with a specific preparation method to obtain a multi-principal-element alloy electrical contact material. Through an equiatomic ratio design, the alloy material exhibits the highest mixing entropy, effectively suppressing the formation of intermetallic compounds and forming a platinum-palladium type FCC solid solution structure with high mixing entropy and high stability. This results in high-temperature stability and high corrosion resistance. Simultaneously, the severe lattice distortion caused by differences in atomic size hinders dislocation movement within the alloy, leading to a significant solid solution strengthening effect that enhances the alloy's hardness and strength. The alloy's hardness and wear resistance are positively correlated; therefore, increased hardness effectively improves the alloy material's wear resistance. Furthermore, by utilizing the differences in solid solubility between alloying elements, combined with solution treatment and aging, fine and uniform Pt-rich second phases are precipitated on the high-entropy alloy solid solution matrix. Then, through the synergistic effect of equiatomic ratio design, solution treatment, and two-stage aging treatment, a coherent two-phase FCC structure is induced (the matrix phase forms a Pd-type lattice, and the precipitated phase forms a Pt-type lattice), achieving a synergistic enhancement mechanism of solid solution strengthening + second-phase strengthening. In the alloy of this invention, the two phases have a high lattice matching degree, ensuring the material's interfacial stability and electron transport performance. Simultaneously, the second phase, as a reinforcing phase, is uniformly distributed in the matrix, significantly improving the material's wear resistance, arc erosion resistance, and high-temperature stability. Finally, utilizing the "cocktail" effect generated by multi-principal element design, the multi-principal element alloy can fully inherit the excellent conductivity of precious metals such as gold and silver, giving the alloy material excellent electrical conductivity.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In one aspect, this invention proposes an Au-Pd-Ag-Pt based multi-principal alloy electrical contact material, wherein the composition of the multi-principal alloy electrical contact material includes Au, Pd, Ag, and Pt, wherein the atomic ratios of Au, Pd, Ag, and Pt are equal.

[0007] Preferably, the multi-principal-element alloy electrical contact material also includes Cu, Ni, and Au, Pd, Ag, Pt, Cu, and Ni in equal atomic ratios.

[0008] In another aspect, this invention provides a method for preparing the above-mentioned multi-principal-element alloy electrical contact material, the method comprising the following steps: The preparation method includes the following steps: (1) Weigh the elemental metal raw materials according to the equiatomic ratio and mix the raw materials to obtain a mixture.

[0009] Because the melt formed by smelting the elemental metal raw materials in this application has poor fluidity, even though the raw materials have been mixed, they are still easy to disperse when the mixture is added to the smelting furnace. It is best to gather the raw materials into a cone shape to help overcome the problem of poor melt fluidity and improve the uniformity of element distribution in the alloy. Therefore, the elemental metal raw materials are preferably in block or granular form (particle size not less than 3 mm, not powder).

[0010] The raw materials can be mixed using conventional mechanical mixing methods, such as mixing them in a stirring device or shaking them in a bag.

[0011] (2) In an inert atmosphere, the mixture obtained in step (1) is smelted and then naturally cooled to obtain an ingot.

[0012] (3) The ingot obtained in step (2) is subjected to solution treatment and then water quenching.

[0013] (4) Perform two-stage aging treatment on the ingot after solution treatment in step (3) to obtain Au-Pd-Ag-Pt multi-principal alloy electrical contact material.

[0014] Preferably, in step (2), arc melting is carried out in an argon-protected environment, and the melting process involves multiple flipping and melting operations. The melting current is 200~300A and the melting time is 25~35min.

[0015] During the electric arc melting process, argon gas has the function of guiding the electric arc.

[0016] The melting process is carried out using a vacuum arc melting furnace with electromagnetic stirring function. During the melting process, the melt is electromagnetically stirred with a stirring current of 10~30A to promote the full mixing of elements, increase homogeneity, and reduce large-scale segregation.

[0017] As a preferred method, the melting process should be repeated at least 8 times, with a turning time every 3 to 4 minutes.

[0018] Preferably, in step (3), the solution treatment temperature is 1000~1250℃ and the holding time is 8~15h.

[0019] Preferably, in step (3), the ingot is immersed in carbon powder before the solution treatment begins.

[0020] Immersing the ingot in carbon powder allows the carbon powder itself, along with the carbon dioxide generated at high temperatures, to isolate it from the air, thus preventing oxidation.

[0021] The particle size of the toner is between 10-50 μm.

[0022] Preferably, in step (4), the first stage of aging treatment is at a temperature of 450~550℃, the holding time is 2~3h, and water quenching is performed after holding.

[0023] Preferably, in step (4), the second stage of aging treatment temperature is 350~450℃, the holding time is 6~8h, and after holding, it is cooled with the furnace or air-cooled.

[0024] The beneficial effects of this invention are: 1. This invention uses gold and silver as conductive matrix elements and platinum and palladium elements to construct a coherent two-phase FCC structure to achieve a synergistic enhancement mechanism of solid solution strengthening + second phase strengthening. Furthermore, it synergizes high entropy effect, lattice distortion effect and "cocktail" effect, thereby giving the alloy electrical contact material superior comprehensive properties such as conductivity, hardness, strength, wear resistance, corrosion resistance and high temperature stability. In addition, the alloy electrical contact material has good performance uniformity.

[0025] 2. This invention promotes the precipitation of the second phase, refines the grains, and reduces segregation by adding Cu and Ni elements, thereby further enhancing the alloy's performance and compensating for the decrease in conductivity caused by the addition of Ni elements.

[0026] 3. This invention reduces segregation problems such as gravity segregation caused by density differences and local segregation caused by melting point differences by using electric arc melting of the mixture, utilizing the eddy current stirring effect of the electromagnetic field and multiple turning melting, thereby promoting the uniform distribution of each component and further enhancing the uniformity of the alloy electrical contact material performance.

[0027] 4. This invention uses high-temperature solution treatment on the ingot to promote the uniform mixing of gold and platinum elements with significant differences in the outer layer structure, which helps to reduce the problem of large-scale segregation in the rough alloy smelting sample.

[0028] 5. The preparation method of this invention is simple and easy to operate, and the prepared electrical contact material has excellent performance and is suitable for industrial application. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process flow of the preparation method of the present invention; Figure 2 Here are the XRD patterns and corresponding PDF cards of the alloy electrical contact material prepared in Example 1 of this invention; Figure 3 The image shown is a SEM-EDS image of the alloy electrical contact material prepared in Example 1 of this invention. Figure 4 Here are the XRD patterns and corresponding PDF cards of the alloy electrical contact material prepared in Example 3 of this invention; Figure 5This is a SEM-EDS image of the alloy electrical contact material prepared in Example 3 of the present invention. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0031] Example 1 This embodiment prepares AuPdAgPt quaternary alloy electrical contact materials using the following method: (1) Weigh out gold ingots, palladium flakes, silver flakes, and platinum granules of 99.9% purity according to the atomic ratio (the mass percentages of gold, palladium, silver, and platinum raw materials calculated according to the atomic ratio are 32.47%, 17.58%, 17.78%, and 32.17%, respectively). Cut and shred the metal raw materials into small gold ingots, small platinum granules, small silver flakes, and small palladium flakes, and mix the small gold ingots, small platinum granules, small silver flakes, and small palladium flakes to obtain a mixture.

[0032] (2) Place the mixture obtained in step (1) into a vacuum arc melting furnace, fill it with argon gas, set the current to 250A, turn on the electromagnetic stirring of the melting furnace, and perform arc melting on the mixture. During the melting process, turn it over once every 3 minutes, for a total of 9 times. After melting for 27 minutes, take out the melt, and after natural cooling, obtain button-shaped AuPdAgPt alloy ingots.

[0033] (3) Place the alloy ingot obtained in step (2) into an alumina corundum crucible, add carbon powder to the crucible until it is fully submerged in the ingot, and tighten the crucible lid; start the box-type resistance furnace and set its heating temperature to 1000℃. After the temperature of the box-type resistance furnace rises to 1000℃, place the crucible in the box-type resistance furnace, keep it at the temperature for 10 hours, take out the crucible, quickly quench it in water, and cool it to room temperature.

[0034] (4) After the solution treatment, the ingot is heated to 500°C, held for 2.5 hours and then water quenched. After that, it is heated to 400°C and held for 7 hours. Then it is air cooled to room temperature to obtain AuPdAgPt four principal alloy electrical contact material.

[0035] XRD and SEM experiments were performed on the four-principal-element alloy electrical contact material prepared in this embodiment, and the results are as follows: Figure 2 , 3 As shown.

[0036] pass Figure 2 and Figure 3It can be seen that the electrical contact material in this embodiment is a four-principal alloy material composed of four elements: Au, Pd, Ag, and Pt. The Pt-rich phase undergoes spheroidization, proving that the Pt element casting is dissolved into the matrix. A coherent two-phase FCC structure of AuPdAgPt matrix phase and Pt-rich phase is formed in the four-principal alloy material. The matrix phase forms a Pd-type lattice, and the Pt-rich phase forms a Pt-type lattice.

[0037] The four-principal-element alloy electrical contact material prepared in this embodiment has a Vickers hardness of 184 HV and a resistivity of 30.89 μΩ·cm.

[0038] Example 2 This embodiment prepares AuPdAgPtCuNi six-principal alloy electrical contact materials using the following method: (1) Weigh out gold ingots, palladium flakes, silver flakes, platinum granules, nickel flakes, and copper flakes with a purity of 99.9% according to the atomic ratio (the mass percentages of gold, palladium, silver, platinum, copper, and nickel raw materials calculated according to the atomic ratio are 27.02%, 14.63%, 14.80%, 26.77%, 8.06%, and 8.72%, respectively). Cut and shear the metal raw materials into small gold ingots, small platinum granules, small silver flakes, small palladium flakes, small nickel flakes, and small copper flakes, and mix the small gold ingots, small platinum granules, small silver flakes, small palladium flakes, small nickel flakes, and small copper flakes to obtain a mixed material.

[0039] (2) Place the mixture obtained in step (1) into a vacuum arc melting furnace, fill it with argon gas, set the current to 200A, turn on the electromagnetic stirring, and perform arc melting on the mixture. During the melting process, turn it over once every 4 minutes, for a total of 8 times. After melting for 32 minutes, take out the melt, and after natural cooling, obtain button-shaped AuPdAgPtNi alloy ingots.

[0040] (3) Place the alloy ingot obtained in step (2) into an alumina corundum crucible, add carbon powder to the crucible until it is fully submerged in the ingot, and tighten the crucible lid; start the box-type resistance furnace and set its heating temperature to 1100℃. After the temperature of the box-type resistance furnace rises to 1100℃, place the crucible in the box-type resistance furnace, keep it at the temperature for 15 hours, take out the crucible, quickly quench it in water, and cool it to room temperature.

[0041] (4) After the solution treatment, the ingot is heated to 450°C, held for 3 hours and then water quenched. After that, it is heated to 350°C and held for 8 hours. Then it is air cooled to room temperature to obtain AuPdAgPtCuNi six-principal alloy electrical contact material.

[0042] The AuPdAgPtCuNi six-principal alloy obtained in this embodiment still forms a two-phase structure: the AuPdAgPtCuNi matrix phase and the NiPt phase. Pt and Pd elements still construct a coherent two-phase FCC structure. The addition of Ni element in this embodiment exacerbated phase separation in the alloy; however, due to the good miscibility of Cu with each principal element across a wide concentration range, its addition alleviated the phase separation phenomenon in AuPdAgPtCuNi. Because Ni has low solid solubility in Ag but extremely high solid solubility in Pt, the Ni phase induces Pt element to dissolve into the matrix, forming a NiPt phase structure distributed in the matrix in a granular or fibrous form.

[0043] The six-principal-element alloy electrical contact material prepared in this embodiment has a Vickers hardness of 280 HV and a resistivity of 40.74 μΩ·cm.

[0044] Example 3 This embodiment prepares AuPdAgPtCuNi six-principal alloy electrical contact materials using the following method: (1) Weigh out gold ingots, palladium flakes, silver flakes, platinum granules, nickel flakes, and copper flakes with a purity of 99.9% according to the atomic ratio (the mass percentages of gold, palladium, silver, platinum, copper, and nickel raw materials calculated according to the atomic ratio are 27.02%, 14.63%, 14.80%, 26.77%, 8.06%, and 8.72%, respectively). Cut and shear the metal raw materials into small gold ingots, small platinum granules, small silver flakes, small palladium flakes, small nickel flakes, and small copper flakes, and mix the small gold ingots, small platinum granules, small silver flakes, small palladium flakes, small nickel flakes, and small copper flakes to obtain a mixed material.

[0045] (2) Place the mixture obtained in step (1) into a vacuum arc melting furnace, fill it with argon gas, set the current to 300A to perform arc melting on the mixture. During the melting process, turn it over once every 3 minutes of melting, and turn it over 10 times in total. After melting for 30 minutes, take out the melt and let it cool naturally to obtain a button-shaped AuPdAgPtCuNi alloy ingot.

[0046] (3) Place the alloy ingot obtained in step (2) into an alumina corundum crucible, add carbon powder to the crucible until it is fully submerged in the ingot, and tighten the crucible lid; start the box-type resistance furnace and set its heating temperature to 1250℃. After the temperature of the box-type resistance furnace rises to 1250℃, place the crucible in the box-type resistance furnace, keep it at the temperature for 8 hours, take out the crucible, quickly quench it in water, and cool it to room temperature.

[0047] (4) The ingot after solution treatment is heated to 550°C, held for 2 hours and then water quenched. After that, it is heated to 450°C and held for 6 hours. Then it is air cooled to room temperature to obtain AuPdAgPtCuNi six-principal alloy electrical contact material.

[0048] XRD and SEM experiments were performed on the six-principal-element alloy electrical contact material prepared in this embodiment, and the results are as follows: Figure 4 , 5 As shown.

[0049] pass Figure 4 and Figure 5 It can be seen that the AuPdAgPtCuNi six-principal alloy obtained in this embodiment is similar to the six-principal alloy obtained in Example 2, possessing an AuPdAgPtCuNi matrix phase and a NiPt phase. Cu exhibits good miscibility with each principal component over a wide concentration range, and its addition can alleviate the phase separation phenomenon of AuPdAgPtCuNi.

[0050] The four-principal-element alloy electrical contact material prepared in this embodiment has a Vickers hardness of 235 HV and a resistivity of 33.36 μΩ·cm.

[0051] Comparative Example 1 This comparative example uses the same method as Example 3 to prepare the AuPdAgPtCuNi hexa-element alloy, the difference being that in this comparative example, the solution treatment temperature is 950℃ and the holding time is 15h.

[0052] In this comparative example, if the solution temperature is too low, it will lead to poor uniformity of element distribution, large-scale segregation, and uneven precipitation of Pt-Pd ordered phase. The ordered phase has poor conductivity, which will significantly reduce the conductivity of the alloy.

[0053] Comparative Example 2 This comparative example uses the same method as Example 3 to prepare the AuPdAgPtCuNi hexa-element alloy, the difference being that in this comparative example, the solution treatment temperature is 1300℃ and the holding time is 8h.

[0054] In this comparative example, excessively high solution temperature can lead to abnormal grain coarsening, loss of material mechanical properties, and volatilization of Ag elements. This causes the alloy to lose its equiatomic ratio characteristics, increases the loss of precious metals, and increases the risk of the solution temperature approaching the solidus line of the material. This can lead to melting and overheating at the grain boundaries, increasing the risk of material failure.

[0055] Comparative Example 3 This comparative example uses the same method as Example 3 to prepare the AuPdAgPtCuNi hexa-element alloy, the difference being that: in this comparative example, an aging treatment is performed at a temperature of 450℃ for 10 hours.

[0056] In this comparative example, the absence of the water-cooling process between the two aging treatments leads to the precipitation of large-scale Pd-rich phases and Pt-Pd phases, which disrupts the phase structure that the multi-principal alloy should have, causing a significant decrease in conductivity. At the same time, it easily causes compositional segregation at grain boundaries, resulting in a decrease in mechanical properties, reducing the phase stability and corrosion resistance of the alloy, and also leading to grain coarsening and uneven distribution of participating stress, further deteriorating mechanical properties.

[0057] In summary, this invention, through optimized design of alloy composition and combined with appropriate preparation methods, successfully obtains an alloy electrical contact material that combines high mixing entropy effect, lattice distortion effect, and "cocktail" effect. This synergistically forms a stable FCC solid solution structure in the alloy, thereby improving the overall performance of the alloy material, such as hardness, strength, wear resistance, and corrosion resistance, and meeting the requirements of practical applications for the comprehensive performance of electrical contact materials.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention 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 the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An Au-Pd-Ag-Pt based multi-principal-element alloy electrical contact material, characterized in that: The multi-principal-element alloy electrical contact material comprises Au, Pd, Ag, and Pt, wherein the atomic ratios of Au, Pd, Ag, and Pt are equal.

2. The Au-Pd-Ag-Pt based multi-principal-element alloy electrical contact material according to claim 1, characterized in that: The multi-principal-element alloy electrical contact material also includes Cu, Ni, and Au, Pd, Ag, Pt, Cu, and Ni in equal atomic ratios.

3. The method for preparing an Au-Pd-Ag-Pt-based multi-principal-element alloy electrical contact material according to claim 1 or 2, characterized in that: The preparation method includes the following steps: (1) Weigh the elemental metal raw materials according to the equiatomic ratio and mix the raw materials to obtain a mixture; (2) In an inert atmosphere, the mixture obtained in step (1) is smelted and then naturally cooled to obtain an ingot. (3) The ingot obtained in step (2) is subjected to solution treatment, followed by water quenching; (4) Perform two-stage aging treatment on the ingot after solution treatment in step (3) to obtain Au-Pd-Ag-Pt multi-principal alloy electrical contact material.

4. The preparation method according to claim 2, characterized in that: In step (2), arc melting is carried out in an argon-protected environment, and the melting process involves multiple flipping and melting operations. The melting current is 200~300A and the melting time is 25~35min.

5. The preparation method according to claim 3, characterized in that: During the smelting process, the surface should be turned over no less than 8 times, once every 3 to 4 minutes of smelting.

6. The preparation method according to claim 2, characterized in that: In step (3), the solution treatment temperature is 1000~1250℃ and the holding time is 8~15h.

7. The preparation method according to claim 2, characterized in that: In step (3), before starting the solution treatment, the ingot is immersed in carbon powder.

8. The preparation method according to claim 2, characterized in that: In step (4), the first stage of aging treatment is at a temperature of 450~550℃ and the holding time is 2~3h. After holding, water quenching is performed.

9. The preparation method according to claim 2, characterized in that: In step (4), the second stage of aging treatment temperature is 350~450℃, the holding time is 6~8h, and after holding, it is cooled with the furnace or air-cooled.

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