Method for preparing high-strength high-conductivity nano-heterostructure copper-chromium-zirconium alloy by multi-stage deformation and multi-stage aging

Abstract

The application belongs to the technical field of non-ferrous metal materials, and particularly discloses a method for preparing high-strength and high-conductivity nano-heterostructure copper-chromium-zirconium alloy through multi-stage deformation and multi-stage aging. The copper-chromium-zirconium alloy has a composition by mass percentage of Cr: 0.5wt%-1.0wt%, Zr: 0.05wt%-0.1wt%, and the balance being copper. The method obtains a new microstructure structure, i.e. a composite structure composed of nano-crystal, nano-twin crystal, nano-precipitated phase and grown micro-precipitated phase. The nano-crystal matrix has a certain component of nano-twin crystal, and is uniformly and diffusely distributed with nano-precipitated phase and part of grown precipitated phase. The new type of copper alloy has a tensile strength of 750MPa-850MPa and an electric conductivity of 75%-80% IACS, and can meet the demand of the electrical and power industries for high-performance copper-chromium-zirconium alloy.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal materials, and specifically discloses a method for preparing high-strength and high-conductivity nano-heterogeneous copper-chromium-zirconium alloys through multi-stage deformation and multi-stage aging. Background Technology

[0002] Following the Industrial Revolution, the steam engine was invented. Railways have become one of the most common and fastest modes of transportation in human society, and copper alloys, due to their high strength and good electrical conductivity, are widely used in lead frames, contact wires, and integrated circuits. With continuous technological advancements, the future will require copper alloys with even higher strength and stronger conductivity.

[0003] Copper-chromium-zirconium alloy, as a raw material for railway contact wires, possesses excellent conductivity and high strength, which can significantly improve the service life of the contact wires and reduce energy loss. With the continuous increase in high-speed rail speeds, the requirements for contact wire strength are also becoming increasingly stringent. Therefore, it is necessary to research and prepare high-strength, high-conductivity (≥650MPa, ≥75% IACS) copper-chromium-zirconium alloys.

[0004] Copper-chromium-zirconium alloys are precipitation-strengthened alloys, forming dispersed phases that hinder dislocation movement and increase alloy strength. Simultaneously, the precipitation of alloying elements reduces the content of solid-solution elements, minimizing the impact on conductivity and resulting in good overall performance. Their production typically involves solution treatment, deformation, and aging; however, these methods offer limited performance improvements and the microstructure of the alloy is uncontrollable, failing to meet the demands of practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide a copper-chromium-zirconium alloy and its preparation method. Traditional service copper alloys contain a large number of coarse grains, a small amount of ultrafine grains, a very small amount of twins, and precipitates. This invention introduces a large number of nanotwins and certain nano and micron precipitates into the copper-chromium-zirconium alloy microstructure to ensure an effective combination of high strength (750–850 MPa) and high electrical conductivity (75%–80% IACS).

[0006] To achieve the objectives of this invention, the method for preparing copper-chromium-zirconium alloy provided by this invention is as follows:

[0007] (1) Solution treatment of copper-chromium-zirconium alloy;

[0008] When the furnace temperature reaches 1000℃, the copper-chromium-zirconium alloy material is placed in the tube furnace and kept at that temperature for 1 hour, then quickly removed and cooled in a 5% NaCl solution.

[0009] The copper-chromium-zirconium alloy used has the following composition and ratio (mass %): Cr: 0.5wt%-1.0wt%, Zr: 0.05wt%-0.1wt%, and the balance being copper.

[0010] The copper is not soluble with chromium, zirconium and other elements at room temperature, but will undergo eutectic transformation when heated to 1000°C, so that the trace elements are uniformly and fully dissolved in the copper matrix; the alloy after the heat preservation treatment in the tube furnace is placed in a 5% NaCl solution for cooling, and a faster cooling speed is more conducive to obtaining a supersaturated solid solution. The copper-chromium-zirconium alloy after the solid solution treatment has good plasticity and toughness, and is convenient for subsequent processing.

[0011] (2) The copper-chromium-zirconium alloy treated in step (1) is subjected to equal channel angular pressing (ECAP) at low temperature, with 1-8 passes of extrusion, an extrusion rate of 10-20 mm / min, an inner angle of 110° and an outer angle of 0° in the die, and an extrusion temperature of -130°C to -100°C;

[0012] (3) The copper-chromium-zirconium alloy treated in step (2) is subjected to rolling at low temperature, with a rolling deformation of 50%, a rolling roller speed of 10-20 r / min, a low-temperature environment of liquid nitrogen, and a rolling temperature of about -130°C to -100°C;

[0013] (4) The copper alloy treated in step (4) is subjected to intermediate aging treatment, with an aging temperature of 100-550°C and an aging time of 0.5-2 hours.

[0014] The low-temperature rolling further deforms the material, which is conducive to the generation of high-density dislocations and nanotwins. With the rolling, the grains are refined, more lamellar structures are generated, nanometer precipitate particles are precipitated and uniformly distributed, and a certain volume fraction of nanotwins and micrometer crystals appear.

[0015] (5) The copper-chromium-zirconium alloy treated in step (4) is subjected to low-temperature rolling, with a rolling deformation of 80%, a rolling roller speed of 10-20 r / min, a low-temperature environment of liquid nitrogen, and a rolling temperature of about -130°C to -100°C;

[0016] During the second low-temperature rolling, the dispersed nanometer precipitate phases generated by the intermediate aging treatment hinder the entanglement of dislocations, forming a large number of dislocation entanglement zones, and some of the precipitate phases are crushed, further improving the strength.

[0017] (6) The copper alloy treated in step (5) is subjected to final aging treatment, with an aging temperature of 100-550°C and an aging time of 0.5-2 hours.

[0018] At the final aging time, part of the precipitated phase precipitated first in the matrix will grow to micron level, and then new nanoscale precipitated phase will be generated, and the strength of the alloy will first slightly decrease and then rise to the highest point.

[0019] The copper-chromium-zirconium alloy prepared by the method is a new microstructure of nanoheterogeneous structure, that is, a complex phase material of nanotwins, nanocrystals and precipitates, that is, nanocrystal matrix dispersed with nanoscale precipitates and micron precipitates.

[0020] The matrix structure of the alloy is nanocrystalline, the nanocrystalline size is ≤200nm, and the volume percentage of nanocrystalline is 55-75%.

[0021] The nanotwins exist in the matrix structure of the alloy, the nanotwin grain size is ≤30nm, and the volume percentage of micron is 15-25%.

[0022] The nanoscale precipitates and part of the micron precipitates are dispersed on the alloy matrix, the nanoscale precipitates have a size of ≤20nm, the micron precipitates have a size of 1-3μm, and the volume percentage of the precipitates is 10-20%.

[0023] Beneficial effects:

[0024] 1. The method prepared is a new nanoheterogeneous structure of nanoheterogeneous structure, that is, a complex structure of nanotwins, nanocrystals and precipitates, which ensures high strength of the material while the conductivity does not decrease obviously, which is due to the effects of grain refinement, twinning, precipitation strengthening and a large number of dislocation tangles. In addition, after intermediate aging treatment, nanoscale precipitates of a certain composition are precipitated on the nanocrystal matrix, and the strength of the alloy is further improved under the precipitation strengthening effect. After final aging, part of the precipitates grow to micron level, and then part of the nanoscale precipitates are precipitated. This breaks through the contradiction between high strength and high conductivity of copper-chromium-zirconium alloy, and realizes the true high strength and high conductivity.

[0025] 2. The simple process flow is conducive to the industrialized preparation of nanoscale high-strength high-conductivity copper-chromium-zirconium alloy; it is green and environmentally friendly, and has certain economic applicability.

[0026] 3. The prepared alloy has excellent performance, which exceeds the performance requirements of the industry for high-strength high-conductivity copper alloy, and meets the needs of high-performance cutting-edge technology. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the process flow chart of the application.

[0028] Figure 2 It is a schematic diagram of the nanoheterogeneous microstructure of the copper-chromium-zirconium alloy.

[0029] Reference numerals: 1, grain boundary with high density of dislocation aggregation; 2, nanotwin; 3, nanosize precipitate dispersedly distributed; 4, microsize precipitate grown.

[0030] Figure 3 is a transmission electron microscope image of the alloy obtained in Example 5; (a) is nanotwin, and (b) is nanosize precipitate phase.

[0031] Figure 4 is a phase composition diagram of the alloy obtained in Example 5. DETAILED DESCRIPTION

[0032] The application is further described in detail below with reference to examples: The thickness of the bulk copper-chromium-zirconium alloy in the following examples is 12 mm, the element content percentage is Cr: 0.5wt%-1.0wt%, Zr: 0.05wt%-0.1wt%, and the balance is Cu. After solid solution treatment at 1000°C for 1h, the alloy is quickly placed in a 5% NaCl solution for cooling. The inner angle of the equal channel extrusion die is 110°, the outer angle is 0°, the extrusion speed is 10-20mm / min, the lubricant is a mixture of MoS2 and machine oil (2:1), the material is extruded in a Ba path mode, and the material is immersed in liquid nitrogen for 10-20min before low-temperature rolling at a rolling speed of 10-20r / min.

[0033] Example 1

[0034] The bulk copper-chromium-zirconium alloy after solid solution treatment has an element content percentage of Cr: 0.5wt%, Zr: 0.05wt%, and the balance is Cu. Then the alloy is subjected to severe plastic deformation, low-temperature equal channel extrusion for 1 pass, low-temperature rolling by 50±1%, single rolling amount is 10%, extrusion and rolling temperature is -130°C to -100°C, the alloy is then aged at 450°C for 1h, followed by low-temperature rolling by 80±1%, single rolling amount is 10%, and finally the alloy is aged at 150°C for 1h. The material is mainly composed of nanocrystalline and nanotwin, and contains a complex phase material composed of nanosize precipitate phase and microsize precipitate phase. The average grain size of the alloy is 200nm, the volume fraction is 85%, the average grain size of the nanotwin is 30nm, the volume fraction is 10%, the average grain size of the nanosize precipitate phase is 20nm, the average grain size of the microsize precipitate phase is 3μm, and the total volume fraction is 5%. The mechanical and electrical properties are tested, the microhardness is 217HV, the tensile strength is 628MPa, and the electrical conductivity is 82%IACS.

[0035] Example 2

[0036] The bulk copper chromium zirconium alloy after solid solution has the element content percentage Cr: 0.8wt%, Zr: 0.08wt%, and the balance is Cu. Then it is subjected to severe plastic deformation, low-temperature equal channel extrusion for 1 pass, low-temperature rolling for 50±1%, single rolling amount is 10%, extrusion and rolling temperature is -130℃ to -100℃, then the alloy is aged at 450℃ for 1h, then low-temperature rolling for 80±1%, single rolling amount is 10%, finally the alloy is aged at 150℃ for 1h. By X-ray diffraction technology and transmission electron microscopy, the material is mainly composed of nanocrystalline and nanotwin, and the complex phase material composed of certain component nanophase and micron phase. The average grain size of the alloy is 200nm, the volume fraction is 80%, the average grain size of the nanotwin is 30nm, the volume fraction is 10%, the average grain size of the nanophase is 20nm, the average grain size of the micron phase is 3μm, and the total volume fraction is 10%. After mechanical property and electrical property test, the microhardness reaches 221HV, the tensile strength is 668MPa, and the conductivity is 80%IACS.

[0037] Example 3

[0038] The bulk copper chromium zirconium alloy after solid solution has the element content percentage Cr: 1.0wt%, Zr: 0.1wt%, and the balance is Cu. Then it is subjected to severe plastic deformation, low-temperature equal channel extrusion for 1 pass, low-temperature rolling for 50±1%, single rolling amount is 10%, extrusion and rolling temperature is -130℃ to -100℃, then the alloy is aged at 450℃ for 1h, then low-temperature rolling for 80±1%, single rolling amount is 10%, finally the alloy is aged at 150℃ for 1h. By X-ray diffraction technology and transmission electron microscopy, the material is mainly composed of nanocrystalline and nanotwin, and the complex phase material composed of certain component nanophase and micron phase. The average grain size of the alloy is 200nm, the volume fraction is 75%, the average grain size of the nanotwin is 30nm, the volume fraction is 15%, the average grain size of the nanophase is 20nm, the average grain size of the micron phase is 3μm, and the total volume fraction is 10%. After mechanical property and electrical property test, the microhardness reaches 227HV, the tensile strength is 698MPa, and the conductivity is 79%IACS.

[0039] Example 4

[0040] The solid-solutioned bulk copper-chromium-zirconium alloy has the following element content percentages: Cr: 1.0 wt%, Zr: 0.1 wt%, and the balance being Cu. Then, the alloy is subjected to severe plastic deformation, low-temperature equal-channel extrusion for 4 passes, low-temperature rolling for 50±1%, single rolling amount being 10%, extrusion and rolling temperature being about -130°C to -100°C, aging the alloy at 450°C for 1 h, then low-temperature rolling for 80±1%, single rolling amount being 10%, and finally aging the alloy at 150°C for 1 h. The material is mainly composed of nanocrystalline and nanotwin, and is a composite material containing nanoscale precipitates and micron-scale precipitates. The average grain size of the alloy is 150 nm, the volume fraction is 65%, the average grain size of the nanotwin is 20 nm, the volume fraction is 20%, the average grain size of the nanoscale precipitates is 15 nm, the average grain size of the micron-scale precipitates is 2 μm, and the total volume fraction is 15%. The microhardness is 245 HV, the tensile strength is 798 MPa, and the electrical conductivity is 78% IACS.

[0041] Example 5

[0042] The solid-solutioned bulk copper-chromium-zirconium alloy has the following element content percentages: Cr: 1.0 wt%, Zr: 0.1 wt%, and the balance being Cu. Then, the alloy is subjected to severe plastic deformation, low-temperature equal-channel extrusion for 8 passes, low-temperature rolling for 50±1%, single rolling amount being 10%, extrusion and rolling temperature being about -130°C to -100°C, aging the alloy at 450°C for 1 h, then low-temperature rolling for 80±1%, single rolling amount being 10%, and finally aging the alloy at 150°C for 1 h. The material is mainly composed of nanocrystalline and nanotwin, and is a composite material containing nanoscale precipitates and micron-scale precipitates. The average grain size of the alloy is 100 nm, the volume fraction is 55%, the average grain size of the nanotwin is 10 nm, the volume fraction is 25%, the average grain size of the nanoscale precipitates is 10 nm, the average grain size of the micron-scale precipitates is 1 μm, and the total volume fraction is 20%. The microhardness is 259 HV, the tensile strength is 830 MPa, and the electrical conductivity is 76% IACS.

[0043] Example 6

[0044] ​The solid-solution bulk copper-chromium-zirconium alloy has the following element content percentage: Cr: 1.0wt%, Zr: 0.1wt%, and the balance of Cu. Then, the alloy is subjected to severe plastic deformation, low-temperature equal-channel extrusion for 8 passes, low-temperature rolling for 50±1%, single rolling amount of 10%, extrusion and rolling temperature of about -130°C to -100°C, aging at 450°C for 1h, then low-temperature rolling for 80±1%, single rolling amount of 10%, and finally aging at 100°C for 1h. The material is mainly composed of nanocrystalline and nanotwin, and is a composite material containing nanoscale precipitates and micron-scale precipitates. The average grain size of the alloy is 100nm, the volume fraction is 60%, the average grain size of the nanotwin is 10nm, the volume fraction is 25%, the average grain size of the nanoscale precipitates is 10nm, the average grain size of the micron-scale precipitates is 1μm, and the total volume fraction is 15%. The microhardness is 244HV, the tensile strength is 800MPa, and the electrical conductivity is 77%IACS.

[0045] Example 7

[0046] The solid-solution bulk copper-chromium-zirconium alloy has the following element content percentage: Cr: 1.0wt%, Zr: 0.1wt%, and the balance of Cu. Then, the alloy is subjected to severe plastic deformation, low-temperature equal-channel extrusion for 8 passes, low-temperature rolling for 50±1%, single rolling amount of 10%, extrusion and rolling temperature of about -130°C to -100°C, aging at 450°C for 1h, then low-temperature rolling for 80±1%, single rolling amount of 10%, and finally aging at 250°C for 1h. The material is mainly composed of nanocrystalline and nanotwin, and is a composite material containing nanoscale precipitates and micron-scale precipitates. The average grain size of the alloy is 100nm, the volume fraction is 50%, the average grain size of the nanotwin is 10nm, the volume fraction is 25%, the average grain size of the nanoscale precipitates is 20nm, the average grain size of the micron-scale precipitates is 5μm, and the total volume fraction is 25%. The microhardness is 235HV, the tensile strength is 750MPa, and the electrical conductivity is 78%IACS.

[0047] Comparative Example 1

[0048] The bulk copper-chromium-zirconium alloy after solid solution has the element content percentage of Cr: 0.5wt%, Zr: 0.05wt%, and the balance of Cu. Then the alloy is subjected to severe plastic deformation, low-temperature rolling of 50±1%, single rolling amount of 10%, rolling temperature of about -130℃ to -100℃, aging of the alloy at 450℃ for 1h, then low-temperature rolling of 80±1%, single rolling amount of 10%, and finally aging of the alloy at 150℃ for 1h. The material is mainly composed of nanocrystalline and nanotwin, and is a composite material containing nanoscale precipitates and micron-scale precipitates. The average grain size of the alloy is 400nm, the volume fraction is 85%, the average grain size of the nanotwin is 35nm, the volume fraction is 10%, the average grain size of the nanoscale precipitates is 25nm, the average grain size of the micron-scale precipitates is 4μm, and the total volume fraction is 5%. The microhardness is 193HV, the tensile strength is 528MPa, and the electrical conductivity is 85%IACS through mechanical property and electrical property tests.

[0049] Comparative Example 2

[0050] The bulk copper-chromium-zirconium alloy after solid solution has the element content percentage of Cr: 0.8wt%, Zr: 0.08wt%, and the balance of Cu. Then the alloy is subjected to severe plastic deformation, equal-channel extrusion at room temperature for 1 pass, low-temperature rolling of 50±1%, single rolling amount of 10%, rolling temperature of about -130℃ to -100℃, aging of the alloy at 450℃ for 1h, then low-temperature rolling of 80±1%, single rolling amount of 10%, and finally aging of the alloy at 150℃ for 1h. The material is mainly composed of nanocrystalline and nanotwin, and is a composite material containing nanoscale precipitates and micron-scale precipitates. The average grain size of the alloy is 400nm, the volume fraction is 85%, the average grain size of the nanotwin is 35nm, the volume fraction is 10%, the average grain size of the nanoscale precipitates is 25nm, the average grain size of the micron-scale precipitates is 4μm, and the total volume fraction is 5%. The microhardness is 216HV, the tensile strength is 628MPa, and the electrical conductivity is 82%IACS through mechanical property and electrical property tests.

[0051] Comparative Example 3

[0052] The solid-solution bulk copper-chromium-zirconium alloy has the following element content percentage: Cr: 1.0wt%, Zr: 0.1wt%, and the balance being Cu. Then, the alloy is subjected to severe plastic deformation, low-temperature equal-channel extrusion for 1 pass, and then room-temperature rolling for 50±1%, with a single rolling amount of 10%, at an extrusion temperature of about -130°C to -100°C. The alloy is then aged at 450°C for 1h, and then room-temperature rolling for 80±1%, with a single rolling amount of 10%. Finally, the alloy is aged at 150°C for 1h. The material is mainly composed of nanocrystals, and is a composite material composed of nanoscale precipitates and micron-scale precipitates. The average grain size of the alloy is 300nm, with a volume fraction of 80%. The average grain size of the nanoscale precipitates is 30nm, and the average grain size of the micron-scale precipitates is 4μm, with a total volume fraction of 20%. The microhardness is 224HV, the tensile strength is 658MPa, and the electrical conductivity is 80%IACS.

[0053] Comparative Example 4

[0054] The solid-solution bulk copper-chromium-zirconium alloy has the following element content percentage: Cr: 1.0wt%, Zr: 0.1wt%, and the balance being Cu. Then, the alloy is subjected to severe plastic deformation, low-temperature equal-channel extrusion for 4 passes, and then low-temperature rolling for 50±1%, with a single rolling amount of 10%, at an extrusion and rolling temperature of about -130°C to -100°C. The alloy is then aged at 450°C for 1h, and then low-temperature rolling for 80±1%, with a single rolling amount of 10%. The material is mainly composed of nanocrystals and nanotwins, and is a composite material composed of nanoscale precipitates. The average grain size of the alloy is 120nm, with a volume fraction of 65%. The average grain size of the nanotwins is 18nm, with a volume fraction of 23%. The average grain size of the nanoscale precipitates is 12nm, with a volume fraction of 12%. The microhardness is 230HV, the tensile strength is 750MPa, and the electrical conductivity is 79%IACS.

[0055] Comparative Example 5

[0056] The solution-treated bulk copper-chromium-zirconium alloy has the following elemental composition: Cr: 1.0 wt%, Zr: 0.1 wt%, with the balance being Cu. It is then subjected to intense plastic deformation, followed by eight passes of equal-channel extrusion and low-temperature rolling at 90 ± 1%, with a single rolling weight of 10%. The extrusion and rolling temperatures are approximately -130℃ to -100℃. Finally, the alloy is aged at 450℃ for 1 hour. X-ray diffraction and transmission electron microscopy characterization revealed that the material is a multiphase material mainly composed of nanocrystals and nanotwins, containing a certain amount of nanoprecipitates. The average grain size of the alloy is 100 nm with a volume fraction of 60%. The average grain size of the nanotwins is 12 nm with a volume fraction of 22%, and the average grain size of the nanoprecipitates is 12 nm with a volume fraction of 18%. Mechanical and electrical property tests showed a microhardness of 240 HV, a tensile strength of 780 MPa, and a conductivity of 77% IACS.

[0057] The room temperature mechanical and electrical conductivity properties of the copper-chromium-zirconium alloy plates of all the above embodiments and comparative examples were tested, and the results are shown in Table 1.

[0058] Table 1 Mechanical and electrical properties of the embodiments and comparative examples

[0059] Hardness (HV) Tensile strength (MPa) Electrical conductivity (% IACS) Example 1 217 628 82 Example 2 221 668 80 Example 3 227 698 79 Example 4 245 798 78 Example 5 259 830 76 Example 6 244 800 77 Example 7 235 750 78 Comparative Example 1 193 528 85 Comparative Example 2 216 628 82 Comparative Example 3 224 658 80 Comparative Example 4 230 750 79 Comparative Example 5 240 780 77

[0060] By comparing the above examples and comparative examples, it can be seen that the strength of the copper-chromium-zirconium plate prepared by this method is improved compared with that of conventional deformation methods. Specifically, by comparing Example 5 and Comparative Example 5, it can be seen that, under the same deformation amount, the tensile strength of the plate without intermediate aging is 50 MPa lower than that of the plate with intermediate aging. This is because the intermediate aging in this invention produces dispersed nano-precipitates, which hinder dislocation movement during secondary rolling, forming dislocation entanglement zones, and some precipitates are broken up, further increasing the strength. By comparing Example 4 and Comparative Example 4, it can be seen that the final aging can precipitate some nano-precipitates again, thereby further improving the alloy strength. Moreover, the peak temperature of the final aging is lower than that of the intermediate aging. This is because during the post-treatment of intermediate aging, Cr / Zr atoms continue to precipitate in the alloy, reducing the system energy, thus reducing the driving force for dislocation recovery, alleviating the recovery degree, and reducing the energy required for subsequent treatment. A comparison of Examples 5 and 7 shows that, under the same deformation, the tensile strength of the over-aged alloy is 48 MPa lower than that of the aging peak. This is because the excessively long aging time leads to the growth of more precipitated phases. Therefore, strictly controlling the degree of under-aging is key to maximizing the advantages of multi-stage deformation-multi-stage aging.

[0061] like Figure 2 As shown, the alloy structure obtained by this process is a novel microstructure—a nano-heterogeneous structure, consisting of nanocrystals + nanotwins + nanoprecipitates + micron-precipitates.

[0062] The embodiments are only used to explain the inventive concept of the present application, and are not intended to limit the right protection of the present application. Any modification made by those skilled in the art without departing from the spirit of the present application shall fall within the scope of the present application.

Claims

1. A high strength high conductivity nanoscale heterogeneous copper-chromium-zirconium alloy prepared by a multistage deformation-multistage aging process, characterized in that, The copper-chromium-zirconium alloy has a composition by mass percentage of Cr: 0.5wt%-0.8wt%, Zr: 0.05wt%-0.1wt%, and the balance being copper; The alloy has a nano-heterogeneous structure, i.e. nanocrystal + nanotwin + nano-precipitate + micro-precipitate; The base structure of the alloy is nanocrystal grain, the nanocrystal grain size is ≤100nm, and the volume percentage of the nanocrystal grain is 55%-75%; the base structure of the alloy has nanotwin, and the nanotwin grain size is ≤30nm; the alloy base is dispersedly distributed with nano-precipitate and part of grown micro-precipitate, the nano-precipitate size is ≤20nm, the micro-precipitate size is between 1-3μm, and the volume percentage of the precipitate is 10%-20%; The preparation method of the high-strength high-conductivity nano-heterogeneous copper-chromium-zirconium alloy comprises the following steps: (1) homogenizing the copper-chromium-zirconium alloy at 1000℃ for 1h under vacuum, and then quickly taking out and cooling in 5% NaCl solution; (2) performing 1-8 pass equal channel angular pressing (ECAP) on the copper-chromium-zirconium alloy treated in step (1) under liquid nitrogen environment; (3) performing rolling deformation with a reduction of 50% on the copper-chromium-zirconium alloy treated in step (2) under liquid nitrogen environment; (4) performing aging treatment on the copper-chromium-zirconium alloy treated by the low-temperature rolling deformation process in step (3); (5) performing secondary rolling deformation with a reduction of 80% on the copper-chromium-zirconium alloy treated in step (4) under liquid nitrogen environment; (6) performing secondary aging treatment on the copper-chromium-zirconium alloy treated by the low-temperature rolling deformation process in step (5); In the rolling deformation process in steps (3) and (5), the rolling speed is 10-20r / min, and the rolling temperature is -130℃--100℃; In steps (4) and (6), the aging temperature is 100-550℃, and the holding time is 0.5-2h.

2. The high strength, high conductivity nanoscale heterogeneous Cu-Cr-Zr alloy produced by multistage deformation-multistage aging of claim 1, wherein, In the equal channel angular pressing process in step (2), the extrusion speed is 10-20mm / min, the inner angle of the die is 110°, the outer angle is 0°, and the extrusion temperature is -130℃--100℃.

3. The high strength and high conductivity nanoscale heterogeneous Cu-Cr-Zr alloy prepared by multi-stage deformation and multi-stage aging according to claim 1, wherein, The alloy has a tensile strength of 750MPa-850MPa and an electrical conductivity of 75%-80% IACS.

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