CrcoNi medium-entropy alloy particle and in-situ self-born nano-phase hybrid reinforced copper-based composite material, preparation method and application thereof

Abstract

This invention discloses a copper-based composite material reinforced with a hybrid of added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, its preparation method, and its application. The method includes: mixing Cu-Al alloy powder sheets and CrCoNi medium-entropy alloy sheets through a wet milling process, followed by vacuum filtration to obtain a composite powder green body; sintering the composite powder green body using a hot pressing sintering process; plastically deforming the sintered composite material using a hot rolling process; and heat-treating the deformed composite material. This invention is based on the in-situ decomposition of CrCoNi medium-entropy alloys, the solid solution of Al atoms and the construction of diffusion channels, and the in-situ self-generated nano-oxide particles formed by the combination of dissolved Cr and Co atoms with oxygen in the copper matrix. This achieves the creation of a copper-based composite material reinforced with a hybrid of added CrCoNi medium-entropy alloy particles and multi-element, multi-scale in-situ self-generated nanophases, breaking through the bottleneck of the inverse relationship between strength and toughness in traditional copper-based composite materials.

Description

Technical Field

[0001] This invention belongs to the field of novel metal matrix composite technology, and specifically relates to a copper matrix composite material reinforced by externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, as well as its preparation method and application. Background Technology

[0002] Pure Cu plays a vital role in many fields due to its excellent electrical and thermal conductivity, and is highly favored by aerospace, railway, military, and electronics industries. However, the inherently low strength of pure Cu significantly limits its application range, making it difficult to meet the growing demands of industrial applications. One effective method to address this issue is to incorporate reinforcing phases into pure Cu to prepare Cu-based composite materials, thereby improving mechanical properties such as room temperature and high temperature strength, hardness, and creep resistance. Currently, ceramic particles, including Al₂O₃, SiC, and TiB₂, are primarily used as reinforcing phases in Cu-based composite materials. Adding a small amount of ceramic particles to composite materials often results in a significant increase in strength, but a rapid decrease in toughness. The main reasons are twofold: (1) The large difference in thermal expansion coefficients and elastic moduli between the ceramic particles and the pure Cu matrix easily generates a stress gradient at the interface during cooling, leading to the initiation and rapid propagation of cracks, making the interface a weak point in the composite material; (2) The poor wettability between the ceramic particles and the pure Cu matrix makes it easy for the ceramic particles to agglomerate and form a metallurgical bonding interface, often resulting in voids at the interface that affect the interfacial bonding strength. To improve this situation, surface coating of the ceramic particles is usually required to improve the wettability, but the complex process undoubtedly increases costs significantly.

[0003] High-entropy and medium-entropy alloys have attracted widespread attention due to their excellent strength, elongation, and high wear resistance. Among them, the ternary medium-entropy alloy CrCoNi exhibits excellent strength and toughness, with tensile strength, elongation at break, and fracture toughness reaching ~1.3 GPa, ~90%, and ~275 MPa·m, respectively. 1 / 2 The metal-metal interface between CrCoNi and the Cu matrix is ​​superior to that between ceramics and metals, exhibiting better interfacial compatibility and wettability, and a smaller difference in the coefficient of thermal expansion between the CrCoNi and the matrix, thus facilitating good interfacial bonding with the metal matrix. However, research on medium-entropy alloy particle-reinforced copper-based composites is quite limited.

[0004] Existing methods for preparing medium-entropy CrCoNi alloy-reinforced Cu-based composites only use pure Cu as the matrix. They do not create conditions to induce the in-situ decomposition of the medium-entropy CrCoNi alloy in the Cu matrix and promote the formation of in-situ self-generated nano-reinforcing phases, thus limiting the improvement of the mechanical properties of Cu-based composites. Summary of the Invention

[0005] To address the shortcomings of the existing technologies, this invention provides a copper-based composite material reinforced with externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, along with its preparation method and applications. This method involves adding Al to a Cu matrix and utilizing the physicochemical properties of the medium-entropy alloy CrCoNi, Al, and the Cu matrix during rapid hot-pressing sintering and heat treatment. This enables the creation of a copper-based composite material reinforced with externally added CrCoNi medium-entropy alloy particles and multi-element, multi-scale in-situ self-generated nanophases. The prepared composite material overcomes the bottleneck of the inverted strength and toughness of traditional copper-based composite materials, and has broad application prospects in key fields such as integrated circuits, high-speed rail transportation, and ultra-high voltage power transmission.

[0006] The first objective of this invention is to provide a method for preparing a copper-based composite material reinforced by an externally added CrCoNi medium-entropy alloy particles and an in-situ self-generated nanophase.

[0007] The second objective of this invention is to provide a copper-based composite material reinforced by an externally added CrCoNi medium-entropy alloy particles and an in-situ self-generated nanophase.

[0008] The third objective of this invention is to provide an application of copper-based composite materials reinforced by an externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases.

[0009] The first objective of this invention can be achieved by adopting the following technical solution:

[0010] A method for preparing a copper-based composite material reinforced with externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases includes the following steps:

[0011] Cu-Al alloy powder sheets and CrCoNi medium-entropy alloy sheets are mixed by wet milling and then vacuum filtered to obtain a composite powder green body. The volume percentage content of the Cu-Al alloy powder sheets and CrCoNi medium-entropy alloy sheets is as follows: Cu-Al alloy powder sheets are 90 vol.%, and CrCoNi medium-entropy alloy sheets are 10 vol.%. The Cu-Al alloy powder sheets contain 0.5–2 wt.% Al powder and 98–99.5 wt.% Cu powder.

[0012] The composite powder green body is sintered and formed using a rapid hot pressing sintering process; wherein the rapid sintering process parameters are: sintering temperature of 850-950℃, sintering pressure of 30-50MPa, sintering time of 30min-1h, and sintering atmosphere of vacuum.

[0013] The sintered composite material is plastically deformed using a hot rolling process;

[0014] The composite material after plastic deformation was subjected to heat treatment to prepare a copper-based composite material reinforced with externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases. The heat treatment included solution treatment followed by water quenching and aging treatment. The solution treatment temperature was 850–950℃ and the solution treatment time was 1–4 h. The aging temperature was 450–600℃ and the aging time was 2–12 h.

[0015] Preferably, the Cu-Al alloy powder sheet is obtained by mixing spherical Cu powder and spherical Al powder and then performing high-energy ball milling; the CrCoNi medium-entropy alloy sheet is obtained by performing high-energy ball milling on spherical CrCoNi powder.

[0016] Preferably, the Al powder has a particle size of 15–45 μm, the Cu powder has a particle size of 50–75 μm, and the CrCoNi powder has a particle size of 30–50 μm.

[0017] Preferably, the high-energy ball milling process parameters are: ball mill speed of 300-500 rpm, ball milling time of 4-8 h, ball-to-material ratio of 5:1-25:1; and ball milling is carried out under an argon protective atmosphere.

[0018] Preferably, Cu-Al alloy powder sheets and CrCoNi medium-entropy alloy sheets are stacked by vacuum filtration and the ball milling media are removed to obtain composite powder green blanks.

[0019] Preferably, the wet milling process parameters are as follows: anhydrous ethanol is used as the ball milling medium, the ball mill speed is 300-400 rpm, the ball-to-material ratio is 3:1-6:1, and the ball milling time is 3-6 hours.

[0020] Preferably, the hot rolling process parameters are: hot rolling holding temperature of 750-850℃ and pressing amount of 30-50%.

[0021] The second objective of this invention can be achieved by adopting the following technical solution:

[0022] A copper-based composite material reinforced by a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases was prepared based on the above-mentioned preparation method.

[0023] The third objective of this invention can be achieved by adopting the following technical solution:

[0024] Applications of a copper-based composite material reinforced with a hybrid of added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, based on the above-mentioned applications of the copper-based composite material reinforced with a hybrid of added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases in integrated circuits, high-speed rail transit, and ultra-high voltage power transmission.

[0025] The present invention has the following advantages over the prior art:

[0026] 1. The CrCoNi medium-entropy alloy particles used in this invention have high strength and toughness, and their thermal expansion coefficient is close to that of Cu. Compared with traditional ceramic particles, they are more likely to form a diffusion metallurgical bonding interface with the Cu matrix.

[0027] 2. The Ni atoms in the CrCoNi medium-entropy alloy particles used in this invention can form an infinite solid solution with Cu, resulting in solid solution strengthening.

[0028] 3. This invention uses a Cu-Al alloy as the matrix. Al is added to the Cu matrix to induce lattice distortion using Al atoms with larger atomic radii, constructing diffusion channels to accelerate the decomposition of CrCoNi reinforcing particles. Cr and Co, desoluble from the CrCoNi entropy alloy particles, diffuse into the Cu matrix through these channels, reacting with residual oxygen from the material preparation process to form in-situ nano-oxide particles (Cr and Co-rich oxide precipitates). This significantly improves the material strength without compromising interfacial bonding strength, thus leveraging the synergistic strengthening effect of the in-situ nano-phase. Furthermore, the addition of Al to the Cu matrix not only produces a solid solution strengthening effect but also reacts in-situ with residual oxygen in the Cu matrix to generate nano-oxide phases, further enhancing the composite material's strength. The resulting composite material not only possesses near-pure Cu plasticity and toughness but also significantly improved strength, exhibiting excellent strength-plasticity matching, breaking through the bottleneck of the inverse relationship between strength and toughness in traditional copper-based composite materials. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0030] Figure 1 The image shown is a scanning electron microscope image of the CrCoNi-reinforced Cu-1.0wt.%Al-based composite material obtained in Example 2 of this invention.

[0031] Figure 2 Typical TEM images and energy dispersive spectroscopy (EDS) of the CrCoNi-reinforced Cu-1.0wt.%Al-based composite material obtained in Example 2 of this invention;

[0032] Figure 3 The transmission electron microscopy characterization results of the CrCoNi reinforced Cu-1.0wt.%Al-based composite material obtained in Example 2 of this invention;

[0033] Figure 4This is a comparison chart of the mechanical properties of the CrCoNi-reinforced Cu-1.0wt.%Al-based composite material obtained in Example 2 of the present invention, the CrCoNi-reinforced Cu-based composite material, and pure Cu.

[0034] Figure 5 The image shown is a scanning electron microscope (SEM) image of the CrCoNi-reinforced Cu-1.5wt.%Al-based composite material obtained in Example 3 of this invention.

[0035] Figure 6 This is a comparison chart of the mechanical properties of the CrCoNi-reinforced Cu-1.5wt.%Al-based composite material obtained in Example 3 of the present invention, the CrCoNi-reinforced Cu-based composite material, and pure Cu. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be understood that the specific embodiments described are merely used to explain this application and are not intended to limit this application.

[0037] Unless otherwise specified, all reagents used in the examples are commercially available.

[0038] The mechanical property data testing method in the following examples is as follows: An MTS E45.305 universal testing machine is used to test the gauge length (10 mm) and cross-section (5 × 3 mm) of the material in the length direction parallel to the rolling direction. 2 Tensile tests were conducted on dog bone-shaped specimens with an initial strain rate of 2.1 × 10⁻⁶. -4 s -1 .

[0039] In the following examples, the Al powder in the Cu-Al alloy powder has a particle size of 15-45 μm, the Cu powder has a particle size of 50-75 μm, and the CrCoNi powder has a particle size of 30-50 μm.

[0040] In the following examples, the high-energy ball milling parameters are: ball mill speed 300-500 rpm, ball milling time 4-8 h, and ball-to-material ratio 5:1-25:1. Within this range, flake Cu-Al alloy powder and flake CrCoNi powder can be obtained.

[0041] In the following examples, the wet milling parameters are as follows: anhydrous ethanol is used as the ball milling medium, the ball mill speed is 300-400 rpm, the ball-to-material ratio is 3:1-6:1, and the ball milling time is 3-6 hours. Within this range, a good mixing effect can be achieved.

[0042] Example 1:

[0043] To prepare a CrCoNi medium-entropy alloy-reinforced Cu-Al based composite material, the raw materials used were 90 vol.% spherical Cu-Al alloy powder and 10 vol.% spherical pure CrCoNi powder. The mass percentage content of Cu powder and Al powder in the Cu-Al alloy powder was 99.5 wt.% Cu powder and 0.5 wt.% Al powder. The raw material powders were weighed according to the powder ratio. Under argon protection, the pure Cu powder and pure Al powder were high-energy ball-milled into flake-shaped Cu-Al alloy powder. The process parameters were: ball mill speed 300 rpm, ball milling time 8 h, and ball-to-powder ratio 25:1. Subsequently, the CrCoNi powder was ball-milled into flakes using the same parameters. Based on this, the Cu-Al alloy powder and flake-shaped CrCoNi powder were ball-milled and mixed in an alcohol medium. The process parameters were: ball mill speed 400 rpm, ball-to-powder ratio 3:1, and ball milling time 3 h. Then, the mixture was vacuum filtered at room temperature to form a green body. The green blank was then sintered in a rapid hot-pressing sintering furnace at 900℃ for 30 min, with a mechanical pressure of 30 MPa applied during sintering under a vacuum atmosphere. The sintered composite material was then hot-rolled after holding at 850℃ for 1 h, with a rolling reduction of 50%. Finally, the composite material was solution-treated at 950℃ for 2 h, water-quenched, and then aged at 450℃ for 2 h to obtain a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, namely, a CrCoNi-reinforced Cu-0.5wt.%Al-based composite material. The prepared CrCoNi-reinforced Cu-0.5wt.%Al-based composite material had a tensile strength of 417.5 MPa and an elongation of 18.5%.

[0044] Example 2:

[0045] A CrCoNi medium-entropy alloy-reinforced Cu-Al based composite material was prepared using 90 vol.% spherical Cu-Al alloy powder and 10 vol.% spherical pure CrCoNi powder. The mass percentage content of Cu and Al powder in the Cu-Al alloy powder was 99.0 wt.% Cu powder and 1.0 wt.% Al powder. The raw material powders were weighed according to the powder ratio. Pure Cu powder and pure Al powder were high-energy ball-milled into flake-shaped Cu-Al alloy powder under argon protection. Subsequently, CrCoNi powder was ball-milled into flakes using the same parameters. Based on this, the Cu-Al alloy powder and flake-shaped CrCoNi powder were ball-milled and mixed in an alcohol medium, and then vacuum-filtered at room temperature to form a green compact. The green compact was then sintered in a rapid hot-pressing sintering furnace at 900℃ for 30 min under a mechanical pressure of 30 MPa and a vacuum atmosphere. The sintered composite material was then hot-rolled after holding at 850℃ for 1 h with a rolling reduction of 50%. Finally, the composite material was solution-treated at 950℃ for 2 hours, then water-quenched, and finally aged at 450℃ for 2 hours to obtain a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, namely, a CrCoNi-reinforced Cu-1.0wt.%Al-based composite material. The prepared CrCoNi-reinforced Cu-1.0wt.%Al-based composite material has a tensile strength of 432.8 MPa and an elongation of 18.8%.

[0046] Figure 1 Scanning electron microscope (SEM) images of CrCoNi-reinforced Cu-1.0wt.%Al-based composites show the decomposition behavior of the CrCoNi-reinforced phase particles. Figure 2 The transmission electron microscopy (TEM) characterization results of the CrCoNi-reinforced Cu-1.0wt.%Al-based composite material show that the CrCoNi reinforcing phase forms a multi-component, multi-scale nano-oxide phase in the Cu-Al matrix. Figure 3 The transmission electron microscopy characterization results of the CrCoNi-reinforced Cu-1.0wt.%Al-based composite material show that a large number of 10-20 nm oxide phases were found in the Cu-Al matrix, indicating that CrCoNi can decompose and diffuse into the Cu-Al matrix in the form of in-situ self-generated nano oxide phases. Figure 4 A comparison of the mechanical properties of CrCoNi-reinforced Cu-1.0wt.%Al-based composite material, 10vol.%CrCoNi-reinforced Cu-based composite material, and pure Cu.

[0047] Example 3:

[0048] A CrCoNi medium-entropy alloy-reinforced Cu-Al based composite material was prepared using 90 vol.% spherical pure Cu-Al alloy powder and 10 vol.% spherical pure CrCoNi powder. The mass percentage content of Cu and Al powder in the Cu-Al alloy powder was 98.5 wt.% Cu powder and 1.5 wt.% Al powder. The raw material powders were weighed according to the powder ratio. Under argon protection, the pure Cu powder and pure Al powder were high-energy ball-milled into flake-shaped Cu-Al alloy powder. Subsequently, the CrCoNi powder was ball-milled into flakes using the same parameters. Based on this, the Cu-Al alloy powder and flake-shaped CrCoNi powder were ball-milled and mixed in an alcohol medium, and then vacuum filtered at room temperature to form a green compact. The green compact was then sintered in a rapid hot-pressing sintering furnace at 900℃ for 30 min under a mechanical pressure of 30 MPa and a vacuum atmosphere. The sintered composite material was then hot-rolled after holding at 850℃ for 1 h with a rolling reduction of 50%. Finally, the composite material was solution-treated at 950℃ for 2 hours, then water-quenched, and finally aged at 450℃ for 2 hours to obtain a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, namely, a CrCoNi-reinforced Cu-1.5wt.%Al-based composite material. The prepared CrCoNi-reinforced Cu-1.5wt.%Al-based composite material has a tensile strength of 491.0 MPa and an elongation of 16.0%.

[0049] Figure 5 The scanning electron microscope image of the CrCoNi-reinforced Cu-1.5wt.%Al-based composite material prepared in this embodiment shows that the decomposition behavior of the CrCoNi-reinforced phase particles is more intense with higher Al content. Figure 6 Comparison of mechanical properties of CrCoNi-reinforced Cu-1.5wt.%Al-based composite material, 10vol.%CrCoNi-reinforced Cu-based composite material, and pure Cu.

[0050] Example 4:

[0051] A CrCoNi medium-entropy alloy-reinforced Cu-2.0 wt.% Al-based composite material was prepared using 90 vol.% spherical pure Cu-Al alloy powder and 10 vol.% spherical pure CrCoNi powder. The mass percentage content of Cu and Al powder in the Cu-Al alloy powder was 98.0 wt.% Cu powder and 2.0 wt.% Al powder. The raw material powders were weighed according to the powder ratio. Pure Cu and pure Al powders were high-energy ball-milled into flake-shaped Cu-Al alloy powder under argon protection. Subsequently, CrCoNi powder was ball-milled into flakes using the same parameters. Based on this, the Cu-Al alloy powder and flake-shaped CrCoNi powder were ball-milled and mixed in an alcohol medium, and then vacuum-filtered at room temperature to form a green compact. The green compact was then sintered in a rapid hot-pressing sintering furnace at 900℃ for 30 min under a mechanical pressure of 30 MPa and a vacuum atmosphere. The sintered composite material was then hot-rolled after holding at 850℃ for 1 h with a rolling reduction of 50%. Finally, the composite material was solution-treated at 950℃ for 2 hours, then water-quenched, and finally aged at 450℃ for 2 hours to obtain a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, namely, a CrCoNi-reinforced Cu-2.0wt.%Al-based composite material. The prepared CrCoNi-reinforced Cu-2.0wt.%Al-based composite material has a tensile strength of 464.0 MPa and an elongation of 12.7%.

[0052] Example 5:

[0053] A CrCoNi medium-entropy alloy-reinforced Cu-1.0 wt.% Al-based composite material was prepared using 90 vol.% spherical pure Cu-Al alloy powder and 10 vol.% spherical pure CrCoNi powder. The mass percentage content of Cu and Al powder in the Cu-Al alloy powder was 99.0 wt.% Cu powder and 1.0 wt.% Al powder. The raw material powders were weighed according to the powder ratio. Pure Cu and pure Al powders were high-energy ball-milled into flake-shaped Cu-Al alloy powder under argon protection. Subsequently, CrCoNi powder was ball-milled into flakes using the same parameters. Based on this, the Cu-Al alloy powder and flake-shaped CrCoNi powder were ball-milled and mixed in an alcohol medium, and then vacuum-filtered at room temperature to form a green compact. The green compact was then sintered in a rapid hot-pressing sintering furnace at 850℃ for 45 min under a mechanical pressure of 40 MPa and a vacuum atmosphere. The sintered composite material was then hot-rolled after holding at 800℃ for 1 h with a rolling reduction of 40%. Finally, the composite material was solution-treated at 900℃ for 1 hour, then water-quenched, and subsequently aged at 600℃ for 6 hours to obtain a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, namely, a CrCoNi-reinforced Cu-2.0wt.%Al-based composite material. The estimated tensile strength of the prepared CrCoNi-reinforced Cu-1.0wt.%Al-based composite material is 430.0 MPa, and the elongation is 13.5%.

[0054] Example 6:

[0055] A CrCoNi medium-entropy alloy-reinforced Cu-1.0 wt.% Al-based composite material was prepared using 90 vol.% spherical pure Cu-Al alloy powder and 10 vol.% spherical pure CrCoNi powder. The mass percentage content of Cu and Al powder in the Cu-Al alloy powder was 99.0 wt.% Cu powder and 1.0 wt.% Al powder. The raw material powders were weighed according to the powder ratio. Pure Cu and pure Al powders were high-energy ball-milled into flake-shaped Cu-Al alloy powder under argon protection. Subsequently, CrCoNi powder was ball-milled into flakes using the same parameters. Based on this, the Cu-Al alloy powder and flake-shaped CrCoNi powder were ball-milled and mixed in an alcohol medium, and then vacuum-filtered at room temperature to form a green compact. The green compact was then sintered in a rapid hot-pressing sintering furnace at 950℃ for 1 h under a mechanical pressure of 50 MPa and a vacuum atmosphere. The sintered composite material was then hot-rolled after holding at 750℃ for 1 h with a rolling reduction of 30%. Finally, the composite material was solution-treated at 850℃ for 2 hours, then water-quenched, and finally aged at 550℃ for 2 hours to obtain a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, namely, a CrCoNi-reinforced Cu-2.0wt.%Al-based composite material. The estimated tensile strength of the prepared CrCoNi-reinforced Cu-1.0wt.%Al-based composite material is 450.0 MPa, and the elongation is 16.5%.

[0056] Example 7:

[0057] A CrCoNi medium-entropy alloy-reinforced Cu-2.0 wt.% Al-based composite material was prepared using 90 vol.% spherical pure Cu-Al alloy powder and 10 vol.% spherical pure CrCoNi powder. The mass percentage content of Cu and Al powder in the Cu-Al alloy powder was 98.0 wt.% Cu powder and 2.0 wt.% Al powder. The raw material powders were weighed according to the powder ratio. Pure Cu and pure Al powders were high-energy ball-milled into flake-shaped Cu-Al alloy powder under argon protection. Subsequently, CrCoNi powder was ball-milled into flakes using the same parameters. Based on this, the Cu-Al alloy powder and flake-shaped CrCoNi powder were ball-milled and mixed in an alcohol medium, and then vacuum-filtered at room temperature to form a green compact. The green compact was then sintered in a rapid hot-pressing sintering furnace at 900℃ for 30 min under a mechanical pressure of 30 MPa and a vacuum atmosphere. The sintered composite material was then hot-rolled after holding at 850℃ for 1 h with a rolling reduction of 50%. Finally, the composite material was solution-treated at 950℃ for 4 hours, then water-quenched, and subsequently aged at 600℃ for 12 hours to obtain a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, namely, a CrCoNi-reinforced Cu-2.0wt.%Al-based composite material. The estimated tensile strength of the prepared CrCoNi-reinforced Cu-2.0wt.%Al-based composite material is 490.0 MPa, and the elongation is 9.6%.

[0058] The sintering methods in all the above embodiments can also be achieved by using sintering methods such as spark plasma sintering and hot isostatic pressing to achieve efficient sintering.

[0059] In summary, the present invention provides a copper-based composite material reinforced with a hybrid of added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, along with its preparation method and application. The preparation method involves high-energy ball milling of spherical Cu-Al alloy powder and CrCoNi powder into sheets, followed by wet milling and vacuum filtration to obtain a composite powder green body. The green body is then sintered using a hot-pressing sintering process. The sintered composite material is then plastically deformed using a hot-rolling process. Finally, the plastically deformed composite material undergoes heat treatment to prepare the copper-based composite material reinforced with a hybrid of added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases. The heat treatment includes solution treatment followed by water quenching and then aging treatment. This invention utilizes the reinforcing effect of medium-entropy alloy CrCoNi particles while simultaneously accelerating the decomposition of CrCoNi reinforcing particles by adding Al to the Cu matrix. This is achieved by using Al atoms with a large atomic radius (1.82 Å) to induce lattice distortion and construct diffusion channels in the copper matrix. The Cr and Co elements desorbed from the CrCoNi reinforcing particles have very low solubility in the Cu matrix and high affinity for O. They can combine with residual oxygen in the Cu matrix to produce nanoscale Cr and Co-rich oxide precipitates, thereby exerting a synergistic reinforcing effect of in-situ nanophases. In addition, the addition of Al to the Cu matrix not only produces a solid solution strengthening effect but also reacts in-situ with residual oxygen in the Cu matrix to generate nano-oxide phases, further improving the strength of the composite material. This invention is based on the in-situ decomposition of CrCoNi medium-entropy alloy, solid solution of Al atoms and construction of diffusion channels, and the combination of desoluble Cr and Co atoms with oxygen in the copper matrix to generate in-situ self-generated nano-oxide particles. This enables the creation of copper-based composite materials reinforced by the addition of CrCoNi medium-entropy alloy particles and multi-element, multi-scale in-situ self-generated nano-phase hybrids. The resulting composite material breaks through the bottleneck of the inversion of strength and toughness in traditional copper-based composite materials.

[0060] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing an externally added CrCoNi medium entropy alloy particle and in-situ self-generated nano-phase hybrid reinforced copper matrix composite material, characterized in that, Includes the following steps: Cu-Al alloy powder sheets and CrCoNi medium-entropy alloy sheets are mixed by wet milling and then vacuum filtered to obtain a composite powder green body. The volume percentage content of the Cu-Al alloy powder sheets and CrCoNi medium-entropy alloy sheets is as follows: Cu-Al alloy powder sheets are 90 vol.%, and CrCoNi medium-entropy alloy sheets are 10 vol.%. The Cu-Al alloy powder sheets contain 0.5–2 wt.% Al powder and 98–99.5 wt.% Cu powder. The composite powder green body is sintered and formed using a rapid hot pressing sintering process; wherein the rapid sintering process parameters are: sintering temperature of 850-950℃, sintering pressure of 30-50MPa, sintering time of 30min-1h, and sintering atmosphere of vacuum. The sintered composite material is plastically deformed using a hot rolling process; The composite material after plastic deformation was subjected to heat treatment to prepare a copper-based composite material reinforced with externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases. The heat treatment included solution treatment followed by water quenching and aging treatment. The solution treatment temperature was 850–950℃ and the solution treatment time was 1–4 h. The aging temperature was 450–600℃ and the aging time was 2–12 h.

2. The preparation method according to claim 1, characterized in that, The Cu-Al alloy powder sheet is obtained by mixing spherical Cu powder and spherical Al powder and then ball milling them at high energy; the CrCoNi medium-entropy alloy sheet is obtained by ball milling spherical CrCoNi powder at high energy.

3. The preparation method according to claim 2, characterized in that, The Al powder has a particle size of 15–45 μm, the Cu powder has a particle size of 50–75 μm, and the CrCoNi powder has a particle size of 30–50 μm.

4. The preparation method according to claim 2, characterized in that, The high-energy ball milling process parameters are as follows: ball mill speed is 300-500 rpm, ball milling time is 4-8 h, and ball-to-material ratio is 5:1-25:1; ball milling is carried out under an argon protective atmosphere.

5. The preparation method according to any one of claims 1 to 4, characterized in that, Cu-Al alloy powder sheets and CrCoNi medium-entropy alloy sheets were stacked by vacuum filtration and the ball milling media were removed to obtain composite powder green bodies.

6. The preparation method according to any one of claims 1 to 4, characterized in that, The wet milling process parameters are as follows: anhydrous ethanol is used as the ball milling medium, the ball mill speed is 300-400 rpm, the ball-to-material ratio is 3:1-6:1, and the ball milling time is 3-6 hours.

7. The preparation method according to any one of claims 1 to 4, characterized in that, The hot rolling process parameters are: hot rolling holding temperature of 750-850℃, and reduction of 30-50%.

8. A copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, characterized in that, It was prepared according to the preparation method described in any one of claims 1 to 7.

9. The application of a copper-based composite material reinforced with a mixture of externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases, characterized in that, Applications of copper-based composite materials reinforced with externally added CrCoNi medium-entropy alloy particles and in-situ self-generated nanophases as described in claim 8 in the fields of integrated circuits, high-speed rail transit, and ultra-high voltage power transmission.

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