High-strength and high-conductivity Cu-Ag-Cr-HEA composite board and preparation method thereof

Abstract

The invention belongs to the technical field of metal materials and composite processing thereof, and discloses a high-strength and high-conductivity Cu-Ag-Cr-HEA composite plate and a preparation method thereof. HEA powder is composed of four refractory elements of Mo, Nb, W and Ta according to the equal molar ratio, the HEA powder and Cr powder are mixed according to the mass ratio of 1: 3 and subjected to ball milling, and Cr-HEA composite powder is obtained; and then the HEA alloy is mixed with Cu powder and Ag powder in proportion, and the Cu-Ag-Cr-HEA alloy is prepared through induction melting at the temperature of 1200-1400 DEG C. And the obtained Cu-Ag-Cr-HEA plates and pure Cu plates are alternately stacked, so that a Cu / Cu-Ag-Cr-HEA layered structure which is periodically and alternately distributed is formed. The tensile strength of the composite material reaches 800 MPa or above, the conductivity is kept at 80% IACS or above, and the composite material is suitable for the fields of high-magnetic-field conductor materials, electrical materials, integrated circuit interconnection materials and high-heat-load electronic packaging materials.

Description

Technical Field

[0001] This invention relates to the field of metal materials and their composite processing technology, specifically to a high-strength, high-conductivity Cu-Ag-Cr-HEA composite plate and its preparation method. Background Technology

[0002] Copper and its alloys are widely used in power, electronics, transportation, and heat exchange industries due to their excellent electrical and thermal conductivity and good processing properties. However, pure copper has relatively low strength, making it difficult to meet the requirements for use under high current density or high mechanical load conditions. In order to improve strength while ensuring high conductivity, alloying, deformation strengthening, precipitation strengthening, and composite methods are commonly used to strengthen and modify copper.

[0003] Among various copper alloy systems, Cu-Ag alloys and Cu-Ag-Cr alloys have attracted widespread attention due to their combination of high strength and excellent electrical conductivity. Ag elements can form nanoscale precipitates in the copper matrix, achieving effective precipitation strengthening; Cr elements can refine grains and suppress high-temperature softening. However, traditional Cu-Ag-Cr alloys still have the following shortcomings: (1) During high-temperature processing and service, the precipitates are prone to coarsening and the strengthening effect is weakened; (2) The alloy strengthening mechanism is simple, making it difficult to further improve strength without significantly reducing electrical conductivity; (3) The distribution of strengthening phases in the alloy structure is uneven, leading to instability in the overall performance of the material. When Cr-rich phases are smelted with Cu, they tend to float due to their low density, resulting in macroscopic segregation.

[0004] Researchers have conducted extensive research on optimizing the performance of Cu-Ag alloys, including various combinations of melting, heat treatment, and deformation processing steps, as well as the addition of other alloying elements. For example, invention patent application CN 202011617275.1 discloses a method for preparing high-strength, high-conductivity copper-silver alloy wire. This alloy mainly consists of 0.2–8.0 wt.% Ag, with total impurities not exceeding 0.1%, and the balance being Cu. The preparation method includes vacuum melting, continuous vacuum casting, aging, and multi-pass drawing. Another example is patent application EP 1911856A1, which discloses a copper-chromium-silver alloy material with a composition ranging from approximately 0.2–0.6 wt.% Cr, 0.005–0.25 wt.% Ag, and the remainder being Cu. This material can be cold-drawn or hot-rolled into fine-diameter wires. Although the above patented technologies improve the strength of Cu-Ag alloys through processing and heat treatment, the difficulty in precisely controlling the size, distribution, and fibrous or layered orientation of the precipitated phases during deformation makes it difficult for Cu-Ag series alloys or composite materials produced by conventional preparation processes to exceed the strength level of approximately 700 MPa.

[0005] Researchers have also conducted in-depth studies on Cu-Cr alloy systems. For example, the copper alloy material and its production method disclosed in application number US20100170595A1 disclose that the copper alloy material contains 0.1-4% by mass of element X (selected from Ni, Fe, Co, Cr, etc.), 0.01-3% by mass of element Y (selected from Ti, Si, Zr, Hf, etc.), and the balance is Cu; this material can obtain a yield strength ≥600 MPa and an electrical conductivity of not less than about 50% IACS through processes such as casting, solution treatment, cold deformation, and aging.

[0006] Although the Cu-Cr system achieves a balance between strengthening and conductivity, significant challenges remain in areas such as high-temperature softening, coarsening of precipitates, microstructure stability, and further improvement of strength without sacrificing conductivity.

[0007] In recent years, high-entropy alloys (HEAs) have been considered a new approach to improving the comprehensive properties of metallic materials due to their high mixing entropy effect, strong solid solution strengthening ability, and excellent thermal stability. In particular, high-entropy solid solutions containing refractory elements such as Mo, Nb, W, and Ta can form high-hardness, high-temperature resistant solid solutions, which play a role in grain refinement and thermal stabilization strengthening in Cu matrices. However, directly introducing the MoNbWTa high-entropy alloy phase into the copper matrix presents problems such as large density difference, poor wettability, and insufficient dispersion uniformity, easily leading to segregation and inclusions during melting. Its density is significantly greater than that of the Cu liquid phase, making it prone to settling during melting and causing macroscopic segregation. Therefore, this invention proposes to form composite particles with the same density as Cu by combining Cr and MoNbWTa phases, thereby avoiding gravity segregation during melting.

[0008] On the other hand, layered composite materials, due to their periodically alternating interfaces, can significantly improve interfacial bonding strength and load transfer capacity, becoming an important approach to achieving synergistic optimization of "high strength and high conductivity". The formation of fine-grained structures and dense interfaces through multiple rolling and heat treatment cycles facilitates synergistic performance regulation.

[0009] However, a review of existing patents and literature reveals that no publicly available reports have been found on this type of technology, which involves introducing high-entropy alloy powder (containing refractory elements such as Mo, Nb, W, and Ta) into a Cu-Ag-Cr matrix and achieving microstructure refinement and precipitation strengthening through a multi-mechanism synergistic enhancement via a layered composite structure.

[0010] In summary, although Cu-Ag, Cu-Cr, and their composite systems have achieved certain performance improvements through the addition of alloying elements and multi-step thermo-mechanical processing, traditional methods still have technological gaps in areas such as strengthening phase distribution control, layered structure construction, balancing conductivity and strength, and high-temperature stability. Therefore, this invention proposes a high-strength, high-conductivity Cu-Ag-Cr-HEA composite plate and its preparation method. Based on the synergistic strengthening of the Cu-Ag-Cr matrix by HEA powder, and through roll forming a periodically alternating layered structure, this high-strength, high-conductivity composite material and its preparation method aim to overcome the aforementioned limitations. Summary of the Invention

[0011] To address the problems of single strengthening mechanisms, difficulty in precise control of microstructure, and difficulty in simultaneously achieving strength and conductivity in existing Cu-Ag, Cu-Cr, and Cu-Ag-Cr alloy systems, this invention proposes a high-strength, high-conductivity Cu-Ag-Cr-HEA composite material and its preparation method. A Cu-Ag-Cr-HEA alloy layer is prepared by combining high-entropy alloy powder (HEA) containing Mo, Nb, W, and Ta with Cu, Ag, Cr, and a small amount of rare earth elements. A multi-layer composite structure is then formed by periodically alternating layers of pure Cu with this composite material using a cumulative lamination method. This invention is primarily applicable to the fields of high-strength, high-conductivity strong magnetic field conductor materials, electrical materials, integrated circuit interconnect materials, and high-heat-load electronic packaging materials.

[0012] The technical solution of the present invention is as follows: a high-strength and high-conductivity Cu-Ag-Cr-HEA composite plate, which is formed by alternating Cu-Ag-Cr-HEA layers and pure Cu layers through a cumulative rolling method to form a multi-layer structure with periodic alternation.

[0013] The Cu-Ag-Cr-HEA layered substrate alloy is composed of the following components by mass percentage: Ag: 2%~10%, Cr: 0.15%~15%, HEA: 0.1%~5%, with the balance being Cu; the HEA is a high-entropy alloy powder containing Mo, Nb, W, and Ta.

[0014] The four elements Mo, Nb, W, and Ta are in equal molar ratios.

[0015] The mass ratio of HEA to Cr is 1:3.

[0016] The Cu-Ag-Cr-HEA layered structure contains uniformly dispersed Cr / HEA composite particles and Ag precipitates.

[0017] The outermost layer of the high-strength, high-conductivity Cu-Ag-Cr-HEA composite plate is made of pure Cu.

[0018] A method for preparing a high-strength, high-conductivity Cu-Ag-Cr-HEA plate, which employs a roll-to-roll method, includes the following steps:

[0019] Step 1: Select Cu-Ag-Cr-HEA alloy plate and pure Cu plate as substrates respectively. The thickness of the substrates is 0.02 mm to 1 mm, and the quantity of each is 2 to 50 pieces.

[0020] Step 2: Anneal the substrate under vacuum or inert atmosphere: anneal the pure Cu plate at 450 °C for 1 hour and the Cu-Ag-Cr-HEA alloy plate at 600 °C for 1 hour to release residual stress and improve interlayer bonding.

[0021] Step 3: The substrate is subjected to ultrasonic acetone degreasing and mechanical polishing to enhance surface roughness;

[0022] Step 4: Stack the substrates alternately, with adjacent layers made of different materials; fix the stacked substrates with an outer jacket, and press them into a composite plate with a thickness of ≤10 mm under a press, with a pressure of 2t / cm²~20t / cm², and hold the pressure for 5~20 minutes;

[0023] Step 5: Heat the composite plate to 800 °C and hold for 10 minutes, then roll it in a hot state with a rolling deformation rate of 40% to 90%.

[0024] Step 6: Remove the outer cover and clean the surface and edges of the composite board;

[0025] Step 7: Cut the composite plate into 2 to 20 small composite plates of the same size. After annealing at 600 °C for 1 hour, use the small composite plates as substrates and repeat steps (3) to (6) a total of 5 times to finally obtain a Cu / Cu-Ag-Cr-HEA composite plate with a periodic alternating structure.

[0026] The preparation method includes the following steps:

[0027] Step 1: Under an inert atmosphere, four refractory elements, Mo, Nb, W and Ta, in equimolar ratios are mixed and ball-milled in a high-energy ball mill to obtain a uniformly mixed HEA solid solution powder.

[0028] Step 2: Mix the HEA solid solution powder and Cr powder according to the required mass percentage, and continue ball milling to obtain Cr-HEA composite powder;

[0029] Step 3: Mix Ag with 2% to 10% by mass, Cr-HEA composite powder with 1% to 20% by mass, and the remainder is Cu powder; ball mill to achieve uniform dispersion of the powder.

[0030] Step 4: Under argon protection, the mixed powder is melted in an induction furnace at 1200°C to 1400°C. The melt is held at this temperature for 3 to 10 minutes and then cast into ingots.

[0031] Step 5: Roll the ingot into a Cu-Ag-Cr-HEA alloy plate.

[0032] The inert atmosphere is an argon atmosphere.

[0033] This invention introduces high-entropy alloy (HEA) powder containing Mo, Nb, W, and Ta elements, along with Cu, Ag, and Cr powders to prepare a Cu-Ag-Cr-HEA matrix. The matrix is ​​then composited with pure Cu layers using an additive additive roll-over (ARB) method, creating a periodically alternating multilayer structure. The synergistic effect of HEA particles and Cr achieves a multi-scale strengthening mechanism, significantly improving the overall performance of the composite material.

[0034] In this invention, HEA powder is composed of four refractory elements—Mo, Nb, W, and Ta—in an equimolar ratio and is prepared by high-energy ball milling. During the smelting process, HEA and Cr are mixed in a density-matched ratio to ensure uniform dispersion in the liquid Cu matrix, reducing segregation caused by density differences. The resulting Cu-Ag-Cr-HEA layer contains finely dispersed Cr / HEA composite particles and nanoscale Ag precipitates, significantly improving the material's strength and thermal stability. After cumulative rolling and heat treatment cycles, the composite material forms a periodic Cu / Cu-Ag-Cr-HEA multilayer structure, achieving synergistic optimization of interfacial strengthening and interlayer electron conduction, thus balancing high strength and high conductivity. In the composite material, the dispersed Cr / HEA composite particles and nanoscale Ag precipitates synergistically strengthen the material, significantly improving its strength and thermal stability while maintaining excellent electrical conductivity.

[0035] The beneficial effects of this invention are:

[0036] (1) By introducing high entropy powder (HEA) with multiple refractory elements, its high thermal stability and high interfacial energy characteristics promote the refinement and dispersion of Cr / HEA composite particles in Cu matrix;

[0037] (2) A periodic alternating structure of Cu and Cu-Ag-Cr-HEA layers is constructed by using a stacking process to achieve a synergistic effect of interface strengthening and grain refinement;

[0038] (3) After multiple rolling and annealing cycles, the composite material obtains an ultrafine-grained multilayer structure with a tensile strength of 800-1000 MPa and an electrical conductivity of over 80% IACS.

[0039] (4) The process of this invention is suitable for continuous preparation and can be extended to fields such as high-strength and high-conductivity copper strips, strong magnetic field conductor materials, motor rotor conductors, rail sliding contact lines and high-frequency interconnect materials. Attached Figure Description

[0040] Figure 1 This is an optical micrograph of the as-cast microstructure of the Cu–6%Ag–3%Cr–1%HEA alloy obtained under melting conditions at 1200 °C in Example 1 of this invention;

[0041] Figure 2 The microstructure of the Cu–6%Ag–3%Cr–1%HEA composite plate after preliminary rolling in Example 4 of the present invention;

[0042] Figure 3 This describes the interfacial bonding morphology of the Cu / Cu-Ag-Cr-HEA composite material prepared by lamination and rolling after Cu-6%Ag-3%Cr-1%HEA alloy powder and pure Cu powder in Example 5 of this invention.

[0043] Figure 4 This describes the interfacial bonding morphology of the Cu / Cu-Ag-Cr-HEA composite material prepared by lamination and rolling after Cu-6%Ag-6%Cr-2%HEA alloy powder and pure Cu powder in Example 6 of the present invention.

[0044] Figure 5 This is the microstructure of the rolled Cu–6%Ag–0.5%Cr alloy (without HEA powder) of Comparative Example 1 of this invention, used to compare the strengthening effect of HEA. Detailed Implementation

[0045] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0046] A high-strength, high-conductivity Cu-Ag-Cr-HEA composite material is disclosed. The composite material is composed of alternating layers of Cu-Ag-Cr-HEA and pure Cu, forming a periodic, parallel, multi-layered structure. The Cu-Ag-Cr-HEA layers are composed of the following components by mass percentage: Ag 2%–10%, Cr 0.15%–15%, HEA 0.1%–5% (the HEA contains Mo, Nb, W, and Ta in equimolar ratios), with the balance being Cu.

[0047] The microstructure of the Cu-Ag-Cr-HEA layer contains dispersed fine Cr / HEA composite particles and Ag precipitates, while the Cu matrix exhibits a fine-grained structure. This microstructure achieves a synergistic effect of precipitation strengthening, particle strengthening, and interface strengthening, significantly enhancing the strength of the composite material while maintaining high electrical conductivity.

[0048] A method for preparing Cu-Ag-Cr-HEA layered material, the method comprising the following steps:

[0049] (1) Under an inert atmosphere, four metal powders, Mo, Nb, W and Ta, were mixed in an equimolar ratio in a high-energy ball mill and ball-milled for 20 hours to obtain uniform HEA powder.

[0050] (2) The HEA powder and Cr powder are mixed at a mass ratio of 1:3 and then ball-milled for 10 hours to prepare Cr-HEA composite powder;

[0051] (3) Mix Cu powder, Ag powder and Cr-HEA composite powder in a certain proportion (Ag 2wt.%~10 wt.%, Cr-HEA composite powder 1wt.%~20wt.%), ball mill for 30 min, then induction melt at 1200°C~1400°C under inert atmosphere protection, hold for 3~10 min and then cast into ingots;

[0052] (4) The ingot is hot rolled and cold rolled to obtain Cu-Ag-Cr-HEA alloy plate.

[0053] A cumulative rolling method for Cu-Ag-Cr-HEA / Cu composite plates, the method comprising the following steps:

[0054] (1) Select 2 to 50 pieces of Cu-Ag-Cr-HEA alloy plate and pure Cu plate with a thickness of 0.02 to 1 mm, and anneal them in vacuum or inert atmosphere respectively: Cu plate at 450 °C × 1 h, Cu-Ag-Cr-HEA plate at 600 °C × 1 h;

[0055] (2) Acetone ultrasonic cleaning and mechanical polishing are used to enhance the interface bonding;

[0056] (3) Assemble the composite billet by alternating Cu layer and Cu-Ag-Cr-HEA layer, constrain it with a stainless steel jacket and hold it under pressure of 2-20 t / cm² for 5-20 min;

[0057] (4) The composite billet is heated to 800 °C and held for 10 min before hot rolling, with a deformation rate of 40-90%;

[0058] (5) After removing the outer jacket, the surface is cleaned and the composite plate is divided into 2 to 20 pieces. After annealing at 600 °C for 1 h, the rolling cycle is repeated 5 times to finally obtain Cu / Cu-Ag-Cr-HEA composite material with a periodic alternating layered structure.

[0059] Preferably, the inert atmosphere is an argon atmosphere.

[0060] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0061] One of the specific implementation methods:

[0062] The raw materials are pure metal Cu, pure metal Ag, pure metal Cr powder, and high entropy alloy (HEA) powder composed of four refractory elements, Mo, Nb, W and Ta, in equimolar ratio.

[0063] Under an inert atmosphere, Cu powder, Ag powder, Cr powder, and HEA powder were first mixed in a specific ratio. The HEA powder was prepared by high-energy ball milling. Mo, Nb, W, and Ta metal powders were ball-milled in equimolar ratio under argon protection for 20 hours to obtain a uniformly mixed high-entropy alloy powder with a particle size of approximately 1–10 μm.

[0064] HEA powder and Cr powder were mixed at a mass ratio of 1:3 and then ball-milled for 10 hours to obtain Cr-HEA composite powder.

[0065] Subsequently, Cu powder, Ag powder and Cr-HEA composite powder were weighed and mixed according to the following mass percentages: Ag 6%, Cr-HEA composite powder 5%, and the balance Cu. The mixture was then mixed at low energy in a ball mill for 30 minutes to ensure that the components were evenly dispersed.

[0066] Under the protection of argon atmosphere, the mixed powder is loaded into a graphite crucible and heated in an induction melting furnace. When the temperature reaches 1300℃, the powder is completely melted. The mixture is held for 5 minutes to allow the components to fully mix and obtain a uniform Cu-Ag-Cr-HEA alloy melt.

[0067] Turn off the induction power supply and pour the alloy melt into a slab copper mold preheated to 200°C with an inner cavity thickness of 20 mm to obtain a Cu-Ag-Cr-HEA alloy slab casting.

[0068] Preferably, the mass of Ag accounts for 2-10% of the total mass of all metal raw materials, more preferably 4-8%, and even more preferably 6%.

[0069] Preferably, the Cr-HEA composite powder accounts for 1-20% of the total mass of all metal raw materials, more preferably 3-10%, and even more preferably 5%.

[0070] Preferably, the molar ratio of the four elements Mo, Nb, W and Ta in the HEA powder is 1:1:1:1.

[0071] Preferably, the inert atmosphere is high-purity argon.

[0072] This invention introduces HEA powder composed of four refractory elements—Mo, Nb, W, and Ta—and mixes it with Cr powder in a density-matched ratio. This avoids particle floating and segregation in the melt, ensuring the uniformity of the alloy microstructure. Under electromagnetic stirring, the Cr / HEA composite particles are finely dispersed in the Cu matrix, while Ag dissolves into the Cu matrix to form a solid solution, providing conditions for the formation of nano-precipitates during subsequent aging treatment.

[0073] By applying a constant magnetic field at a horizontal level, melt convection was suppressed, stabilizing the macroscopic flow environment of the melt and resulting in a more uniform distribution of Cr / HEA particles, thus avoiding macroscopic segregation. Microscopic observation of the prepared Cu-Ag-Cr-HEA alloy slab revealed fine matrix grains and a dispersed distribution of Cr / HEA particles and Ag precipitates, significantly improving the material's strength and thermal stability.

[0074] Example 1

[0075] A Cu-6%Ag-5%(Cr-HEA) alloy and its preparation method are as follows:

[0076] The raw materials are pure Cu powder, pure Ag powder, pure Cr powder, and high-entropy alloy powder (composed of Mo, Nb, W, and Ta in a molar ratio of 1:1:1:1). The content of each element by weight percentage is: Ag 6%, Cr-HEA composite powder 5%, and Cu as the balance.

[0077] HEA powder was obtained by ball milling Mo, Nb, W and Ta powders in a high-energy ball mill for 20 hours under an inert atmosphere. The HEA powder and Cr powder were then mixed at a mass ratio of 1:3 and ball milled for 10 hours to obtain Cr-HEA composite powder.

[0078] Subsequently, Cu powder, Ag powder and Cr-HEA composite powder were mixed for 30 minutes and then melted in an induction melting furnace at 1300℃ for 5 minutes. After stirring evenly, the induction power was turned off.

[0079] The melt was injected into a copper mold with an inner cavity thickness of 20 mm to obtain a Cu-6%Ag-5%(Cr-HEA) alloy slab.

[0080] Observed under a metallographic microscope and a scanning electron microscope, such as Figure 1 As shown, the alloy microstructure consists of a fine equiaxed Cu matrix, dispersed Cr / HEA composite particles, and nanoscale Ag precipitates with particle sizes ranging from approximately 50 to 200 nm and uniform distribution. This microstructure effectively suppresses macroscopic segregation and significantly improves the strength and thermal stability of the Cu matrix.

[0081] The Cu-6%Ag-5%(Cr-HEA) alloy prepared in this embodiment has a tensile strength of approximately 1150 MPa and a conductivity of approximately 75% IACS, demonstrating excellent strength-conductivity matching performance.

[0082] Example 2

[0083] The method is the same as in Example 1, except that:

[0084] (1) The content of each element by mass percentage is: Ag 8%, Cr-HEA composite powder 3%, and the balance Cu.

[0085] (2) The thickness of the inner cavity of the copper mold is 20 mm.

[0086] The preparation method in this embodiment produces a Cu-8%Ag-3%(Cr-HEA) alloy slab with a dispersed distribution of Cr / HEA composite particles and nano-Ag precipitates. The microstructure is uniform, and the Cu matrix grains are fine. The alloy has a tensile strength of approximately 960 MPa and a conductivity of approximately 78% IACS.

[0087] Example 3

[0088] The method is the same as in Example 1, except that:

[0089] (1) The content of each element by mass percentage is: Ag 4%, Cr-HEA composite powder 5%, and the balance Cu.

[0090] (2) The thickness of the inner cavity of the copper mold is 10 mm.

[0091] The preparation method in this embodiment produces a Cu-4%Ag-5%(Cr-HEA) alloy slab with uniformly distributed Cr / HEA composite particles and nano-Ag precipitates, such as... Figure 2 As shown in the figure, its microstructure features fine Cu matrix grains, uniform distribution of Cr / HEA composite particles and Ag precipitates, a tensile strength of approximately 10¹⁰ MPa, and a conductivity of approximately 80% IACS.

[0092] Example 4

[0093] The method is the same as in Example 1, except that:

[0094] (1) The content of each element by mass percentage is: Ag 10%, Cr-HEA composite powder 2%, and the balance Cu.

[0095] (2) The thickness of the inner cavity of the copper mold is 5 mm.

[0096] This embodiment describes the preparation method for a Cu-10%Ag-2%(Cr-HEA) alloy slab with a dispersed distribution of Cr / HEA composite particles and nano-Ag precipitates. The alloy matrix has fine grains, uniformly distributed composite particles, a tensile strength of approximately 860 MPa, and a conductivity of approximately 83% IACS.

[0097] Example 5

[0098] The method is the same as in Example 1, except that:

[0099] (1) The content of each element by mass percentage is: Ag 2%, Cr-HEA composite powder 1%, and Cu as the balance.

[0100] (2) The thickness of the inner cavity of the copper mold is 0.5 mm.

[0101] The preparation method in this embodiment produces a Cu-2%Ag-1%(Cr-HEA) alloy slab with Cr / HEA composite particles and nano-Ag precipitates dispersedly. Figure 3 As shown, its Cu matrix has fine grains, and the Cr / HEA composite particles and Ag precipitates are uniformly distributed. The tensile strength is approximately 610 MPa, and the electrical conductivity is approximately 90% IACS.

[0102] Comparative Example 1

[0103] The method is the same as in Example 3, except that:

[0104] The content of each element by mass percentage is: Ag 4%, Cr 0.5%, no high entropy alloy (HEA) composite powder added, and the balance is Cu.

[0105] The comparative preparation method yielded a Cu-4%Ag-0.5%Cr alloy slab, such as... Figure 4 As shown in the figure, the Cu matrix grains in the microstructure are relatively large. Although the microstructure was refined after rolling deformation, no fine and dispersed Cr / HEA composite phase was observed. Ag precipitates in the alloy are segregated at the grain boundaries. The tensile strength of this alloy is approximately 470 MPa, and the electrical conductivity is approximately 87% IACS.

[0106] Compared with Example 3, the comparative alloy in this example lacks the dispersed distribution of the Cr / HEA composite strengthening phase, resulting in limited matrix strengthening effect and significantly reduced strength. This indicates that HEA particles play a significant role in promoting grain refinement and precipitation homogenization.

[0107] Comparative Example 2

[0108] The method is the same as in Example 1, except that:

[0109] The content of each element by mass percentage is: Ag 6%, with 6% added high entropy alloy (HEA) composite powder, and the balance being Cu.

[0110] The preparation method in this embodiment produces a Cu-6%Ag-6%(Cr-HEA) alloy slab with a uniform distribution of Cr / HEA composite particles and nano-Ag precipitates, but the Cr / HEA composite particles are significantly larger. The tensile strength is approximately 1190 MPa, and the electrical conductivity is approximately 71% IACS.

[0111] Compared with Example 1, the comparative alloy showed a significant matrix strengthening effect due to the addition of excessive Cr-HEA high-entropy alloy composite powder, but the conductivity was significantly reduced. This indicates that adding too much Cr-HEA high-entropy composite powder has a significant impact on the conductivity of the alloy, and the improvement in strength is not significant.

[0112] Comparative Example 3

[0113] The method is the same as in Example 1, except that:

[0114] The content of each element by mass percentage is: Ag 6%, with 0.5% added high entropy alloy (HEA) composite powder, and the balance being Cu.

[0115] The preparation method in this embodiment produces a Cu-6%Ag-0.5%(Cr-HEA) alloy slab with a uniform distribution of Cr / HEA composite particles and nano-Ag precipitates, but the Cr / HEA composite particles are significantly larger. The tensile strength is approximately 680 MPa, and the electrical conductivity is approximately 75% IACS.

[0116] Compared with Example 1, the comparative alloy showed no significant matrix strengthening effect due to the addition of a small amount of Cr-HEA high-entropy alloy composite powder, but the conductivity was not greatly improved either. This indicates that adding a small amount of Cr-HEA high-entropy composite powder has a significant impact on the conductivity of the alloy, but the improvement in strength is not significant.

Claims

1. A high-strength, high-conductivity Cu-Ag-Cr-HEA composite material, characterized in that, It is formed by alternating Cu-Ag-Cr-HEA layers and pure Cu layers through a cumulative rolling process, resulting in a multilayer structure with periodic alternation.

2. The high-strength, high-conductivity Cu-Ag-Cr-HEA composite material according to claim 1, characterized in that, The Cu-Ag-Cr-HEA layered substrate alloy is composed of the following components by mass percentage: Ag: 2%~10%, Cr: 0.15%~15%, HEA: 0.1%~5%, with the balance being Cu; the HEA is a high-entropy alloy powder containing Mo, Nb, W, and Ta.

3. The high-strength, high-conductivity Cu-Ag-Cr-HEA composite material according to claim 2, characterized in that, The four elements Mo, Nb, W, and Ta are in equal molar ratios.

4. The high-strength, high-conductivity Cu-Ag-Cr-HEA composite material according to claim 2, characterized in that, The mass ratio of HEA to Cr is 1:

3.

5. The high-strength, high-conductivity Cu-Ag-Cr-HEA composite material according to claim 4, characterized in that, The Cu-Ag-Cr-HEA layered structure contains uniformly dispersed Cr / HEA composite particles and Ag precipitates.

6. The high-strength, high-conductivity Cu-Ag-Cr-HEA composite material according to claim 1, characterized in that, The outermost layer of the high-strength, high-conductivity Cu-Ag-Cr-HEA composite plate is made of pure Cu.

7. A method for preparing a high-strength, high-conductivity Cu-Ag-Cr-HEA substrate according to any one of claims 1-6, characterized in that, The material is prepared using a roll-over method, including the following steps: Step 1: Select Cu-Ag-Cr-HEA alloy plate and pure Cu plate as substrates respectively. The thickness of the substrates is 0.02 mm to 1 mm, and the quantity of each is 2 to 50 pieces. Step 2: Anneal the substrate under vacuum or inert atmosphere: anneal the pure Cu plate at 450 °C for 1 hour and the Cu-Ag-Cr-HEA alloy plate at 600 °C for 1 hour to release residual stress and improve interlayer bonding. Step 3: The substrate is subjected to ultrasonic acetone degreasing and mechanical polishing to enhance surface roughness; Step 4: Stack the substrates alternately, with adjacent layers made of different materials; fix the stacked substrates with an outer jacket, and press them into a composite plate with a thickness of ≤10 mm under a press, with a pressure of 2t / cm²~20t / cm², and hold the pressure for 5~20 minutes; Step 5: Heat the composite plate to 800 °C and hold for 10 minutes, then roll it in a hot state with a rolling deformation rate of 40% to 90%. Step 6: Remove the outer cover and clean the surface and edges of the composite board; Step 7: Cut the composite plate into 2 to 20 small composite plates of the same size. After annealing at 600 °C for 1 hour, use the small composite plates as substrates and repeat steps 3 to 6 a total of 5 times to finally obtain a Cu / Cu-Ag-Cr-HEA composite plate with a periodic alternating structure.

8. The preparation method according to claim 7, characterized in that, Includes the following steps: Step 1: Under an inert atmosphere, four refractory elements, Mo, Nb, W and Ta, in equimolar ratios are mixed and ball-milled in a high-energy ball mill to obtain a uniformly mixed HEA solid solution powder. Step 2: Mix the HEA solid solution powder and Cr powder according to the required mass percentage, and continue ball milling to obtain Cr-HEA composite powder; Step 3: Mix Ag with 2% to 10% by mass, Cr-HEA composite powder with 1% to 20% by mass, and the remainder is Cu powder; ball mill to achieve uniform dispersion of the powder. Step 4: Under argon protection, the mixed powder is melted in an induction furnace at 1200°C to 1400°C. The melt is held at this temperature for 3 to 10 minutes and then cast into ingots. Step 5: Roll the ingot into a Cu-Ag-Cr-HEA alloy plate.

9. The method for preparing the high-strength, high-conductivity Cu-Ag-Cr-HEA composite material according to claim 7 or 8, characterized in that, The inert atmosphere is an argon atmosphere.

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