A method for obtaining high-strength high-conductivity copper alloy by preparing gradient twin

Abstract

This invention discloses a method for obtaining high-strength, high-conductivity copper alloys through gradient twinning, belonging to the field of high-strength, high-conductivity electronic device fabrication technology. The fabrication method includes: obtaining plates with various texture orientations through directional solidification technology, stacking them sequentially from hard orientation to soft orientation to prepare multilayer plates with different texture orientations, and then performing cumulative roll bonding on the multilayer plates. Through this method, the gradient twinned copper alloy prepared by this invention can effectively improve the conductivity of the alloy while increasing its strength. This design and fabrication method for high-strength, high-conductivity copper alloys has significant guiding significance for adapting to the development of industries such as electronics and information, future transportation, and aerospace, and has very good industrial application prospects.

Description

TECHNICAL FIELD

[0001] The application relates to a method for obtaining a high-strength high-conductivity copper alloy by preparing gradient twins, and belongs to the technical field of high-strength high-conductivity electronic device preparation. BACKGROUND

[0002] The high-strength high-conductivity copper alloy is not only a basic material for national economic construction, but also a key material in many high-tech fields, and is widely used in new energy vehicles, aerospace, high-speed railways, electronic information and other fields. These fields not only require copper and copper alloy materials to have sufficient strength, hardness and other properties, but also need to maintain good electrical conductivity. In order to meet the performance of high-strength high-conductivity copper alloy, the strengthening method of the alloy is constantly changing. The strengthening method of alloying is to form micro defects in the material. This process is mature and easy to operate, but the existence of micro defects slows down the number of electrons moving in the crystal, and the electrical conductivity is generally less than 60% IACS. The composite material method greatly improves the strength of the material, but the operation process is complex, the production cost is high, and it is difficult to carry out industrialized production.

[0003] Patent CN114990376B discloses a ternary high-strength high-conductivity copper alloy and a preparation method thereof; a new type of ternary high-strength high-conductivity copper alloy and a preparation method thereof are provided. The copper alloy contains Fe, Zr and Cu, wherein the mass percentage of Fe and Zr in the copper alloy is 0.1% to 1.0%, and the balance is copper; and the atomic ratio of the two is between 1.9 and 2.7; the preparation method of the copper alloy is provided. The Cu-Fe-Zr alloy ingot is obtained by induction melting, and then the ingot is subjected to solid solution, rolling and isothermal aging treatment, so that Fe-2Zr compounds are precipitated in the alloy; the copper alloy prepared has a conductivity of 70% IACS, but the tensile strength is only 500 MPa.

[0004] Patent CN116623071A discloses a high-strength high-conductivity copper alloy sheet and a preparation method thereof; which comprises the following steps: S1, batching: preparing raw materials; S2, melting: melting the raw materials; S3, casting: casting the melt; S4, hot rolling: hot rolling the ingot; S5, solid solution: solid solution of the hot rolled blank; S6, face milling: removing the solid solution blank surface oxide skin; S7, primary rolling: primary rolling of the blank after face milling; S8, annealing: annealing treatment of the primary rolled sheet; S9, finish rolling: finish rolling of the annealed sheet; S10, annealing: annealing treatment of the finish rolled sheet; the alloy strengthening is mainly deformation strengthening + aging strengthening, and after aging treatment, the alloy is dispersedly distributed with strengthening phases, mainly single element Cr, Cu3Zr and NiX phase. The key is to adjust and deploy NiX combination to ensure that the added elements are fully precipitated and the influence on electrical conductivity is minimized. The copper alloy prepared has a tensile strength of 742 MPa and an electrical conductivity of 72.2% IACS.

[0005] The copper alloy material obtained by the above process has very low tensile strength while improving the electrical conductivity of the copper alloy through the operation, and cannot simultaneously consider strength and electrical conductivity, and the performance of the tensile strength greater than 700 MPa and the electrical conductivity greater than 70% IACS cannot meet the requirements of future production of high-strength and high-conductivity copper alloys while the operation is complex. Therefore, it is necessary to provide a preparation method which can improve the strength and electrical conductivity of the copper alloy, adapt to the development requirements of future high-strength and high-conductivity copper alloys, and further expand the application of high-strength and high-conductivity copper alloy materials in various industries. SUMMARY

[0006] In view of the shortcomings of the prior art, the purpose of the present application is to provide a method for obtaining high-strength and high-conductivity copper alloy by preparing gradient twins, and to prepare a multi-layer plate with different texture directions by sequentially stacking in order from hard orientation to soft orientation, and then to perform cumulative roll bonding on the multi-layer plate. The prepared gradient twin copper alloy can effectively improve the electrical conductivity of the alloy while improving the strength of the copper alloy, so as to achieve the processing goal of simultaneously considering the mechanical properties and electrical properties of the copper alloy.

[0007] The technical scheme of the present application is as follows, specifically comprising the following steps:

[0008] (1) preparing copper alloy plates with different textures, and cutting the copper alloy plates with different textures into copper alloy plates of the same size.

[0009] (2) sequentially stacking several copper alloy plates with different textures in order from hard orientation to soft orientation to obtain a copper alloy multi-layer plate with different texture directions stacked in order from hard orientation to soft orientation, so as to ensure that the anisotropy of each layer of the copper alloy plate is different, and to expand the anisotropy of the material in the subsequent rolling and heat treatment process, thereby realizing the formation of gradient twins.

[0010] (3) performing cumulative roll bonding on the copper alloy multi-layer plate, i.e. cutting the plate into two halves after each rolling, and then stacking them together in the order of hard orientation on top and soft orientation on the bottom, and performing the next rolling, and so on, wherein the rolling temperature is increased step by step, the rolling compression ratio is decreased step by step, and the rolling times are not less than 4, so as to realize large deformation and multiple rollings of the plate, thereby improving the twin content and strength of the plate, and improving grain refinement and twin formation, so as to prepare a gradient twin.

[0011] (4) annealing and heat treating the material after cumulative roll bonding, and the cooling method is furnace natural cooling.

[0012] Preferably, the copper alloy plates with different textures in step (1) of the present application are prepared by using directional solidification technology.

[0013] Preferably, the rolling temperature in step (3) of the present application is 400-600 DEG C, the rolling compression ratio is 20-50%, and the rolling temperature is increased and the rolling compression ratio is decreased gradually with the rolling.

[0014] Preferably, the annealing temperature in step (4) of the present application is 500-800 DEG C, and the annealing time is 0.5-2h.

[0015] The principle of the present application: directional solidification is a commonly used method for controlling the solid phase transition process of metals, which can form a unified crystal orientation in the alloy during solidification by controlling the temperature gradient and solidification speed during solidification, that is, the texture we call; this method is mainly applied to the preparation of alloy materials with specific properties, such as high-temperature alloys, hard alloys, etc.; the present application obtains multiple copper alloy plates with different textures of the same thickness by directional solidification method, which are (111), (221), (211), (110), (210), (310) and (100) orientations; then seven copper alloy plates with different textures are stacked in order from hard orientation to soft orientation, that is, stacked in the order of (111), (221), (211), (110), (210), (310) and (100) textures, to obtain a multilayer plate with different texture directions stacked in order from hard orientation to soft orientation, and expand its anisotropy. In the subsequent cumulative roll bonding process, due to the difference in the microstructure of each layer and the gradient change of the twin density formed by the difference in the soft and hard orientations of the adjacent textures, a C7035 copper alloy with gradient density twins is formed, achieving the purpose of high-strength and high-conductivity copper alloy.

[0016] The beneficial effects of the present application are:

[0017] The excellent effects of the present application mainly lie in that the above-mentioned processing technology causes the material to produce gradient density twins, which can improve the strength of the material while ensuring its high conductivity; it can improve the performance of the material by changing the microstructure and grain orientation of the material without changing the chemical composition of the material.

[0018] In general, the principle and excellent effects of the present application mainly lie in its unique processing technology and structural design, which can make the material maintain high strength while also having good electrical conductivity, thereby greatly improving the performance of the material; this undoubtedly opens up new possibilities for the research and application of copper alloy materials. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a schematic diagram of the gradient twin material of the present application.

[0020] Figure 2A schematic diagram of the texture of C7035 copper alloy and a diagram of elastic modulus of main crystal direction thereof. DETAILED DESCRIPTION

[0021] For the purpose, technical scheme and advantages of the present application, the present application will be further described below in combination with specific examples; however, the protection scope of the present application is not limited to the content described below.

[0022] The present application is described by taking C7035 copper alloy as an example, and the chemical composition thereof is shown in Table 1.

[0023] Table 1 Chemical composition of copper alloy (wt%)

[0024] Ni Si Co Cu and unavoidable impurities 1.5 0.6 1.1 balance

[0025] The specific preparation method is as follows:

[0026] (1) Seven kinds of C7035 copper alloy plates with different textures of (111), (221), (211), (110), (210), (310) and (100) are prepared by using directional solidification technology, and the seven orientations represent the change of the texture from hard orientation to soft orientation, thereby giving the material obvious anisotropy characteristics. The copper alloy plates with different textures are cut into plates with the same size.

[0027] (2) The seven kinds of copper alloy plates with different textures are stacked in order from hard orientation to soft orientation, i.e., stacked in the order of (111), (221), (211), (110), (210), (310) and (100) textures, to obtain a multi-layer plate with different texture directions stacked in order from hard orientation to soft orientation, so as to ensure that the anisotropy of each layer of the plate is different, and the anisotropy of the material is expanded in the subsequent rolling and heat treatment process, thereby realizing the formation of gradient twin crystals.

[0028] The seven kinds of copper alloy plates with different textures are stacked in order from soft orientation to hard orientation, so that the material has different anisotropy due to different texture directions, and in the rolling process, the copper alloy plates with different textures have different deformation degrees and twin crystal contents, thereby causing the gradient change of the strength and conductivity of the material; and in the heat treatment process, the copper alloy plates with different textures have different recovery and recrystallization behaviors, thereby causing the gradient change of the grain size and twin crystal density of the material.

[0029] (3) The multi-layer plate is subjected to accumulative roll bonding welding, that is, after each rolling, the plate is cut into two halves, and then stacked together in the order of hard orientation on top and soft orientation on bottom, and subjected to the next rolling, and so on, wherein the rolling temperature is increased gradually, the rolling compression ratio is decreased gradually, and the rolling number is not less than 4, so as to realize large deformation and multiple rollings of the plate, thereby increasing the twin crystal content and strength of the plate, and improving grain refinement and twin crystal formation, so as to prepare a plate with gradient twin crystals.

[0030] (4) The material after accumulative roll bonding welding is subjected to annealing heat treatment, wherein the annealing temperature is 500-800℃, the annealing time is 0.5-2h, and the cooling mode is furnace natural cooling.

[0031] Example 1

[0032] The preparation method of the high-strength and high-conductivity copper alloy in the embodiment specifically comprises the following steps:

[0033] (1) Raw materials of the copper alloy with the components shown in Table 1 are prepared, and Cu, Ni, Si and Co are melted according to the contents shown in Table 1 to obtain a copper alloy base.

[0034] (2) A plurality of copper alloy plates with different textures and the same thickness are obtained by directional solidification technology, which are (111), (221), (211), (110), (210), (310) and (100) orientations respectively, and the copper alloy plates with different textures are cut into the same size, and the seven orientations represent the texture change from hard orientation to soft orientation, thereby giving the material obvious anisotropy characteristics.

[0035] (3) The seven copper alloy plates with different textures are stacked in order from hard orientation to soft orientation, that is, stacked in the order of (111), (221), (211), (110), (210), (310) and (100) textures, to obtain a multi-layer plate with different texture directions stacked in order from hard orientation to soft orientation.

[0036] (4) The multi-layer plate is subjected to accumulative roll bonding welding, that is, after each rolling, the plate is cut into two halves, and then stacked together in the order of hard orientation on top and soft orientation on bottom, and subjected to the next rolling, and so on, wherein the rolling temperature is increased gradually, the rolling compression ratio is decreased gradually, and the rolling number is not less than 4, so as to realize large deformation and multiple rollings of the plate, thereby increasing the twin crystal content and strength of the plate, and improving grain refinement and twin crystal formation, so as to prepare a plate with gradient twin crystals.

[0037] (5) annealing heat treatment is performed on the material after accumulative roll-bonding, wherein the annealing temperature is 500℃, the annealing time is 0.5h, and the cooling mode is furnace natural cooling.

[0038] The tensile strength and electrical conductivity of the high-strength and high-conductivity copper alloy finally obtained are shown in Table 2:

[0039] Table 2 Performance test results of copper alloy of Example 1 of the present application

[0040] Tensile strength / MPa Electrical conductivity / % IACS 810.1 78.9

[0041] Example 2

[0042] The preparation method of the high-strength and high-conductivity copper alloy described in this example specifically includes the following steps:

[0043] (1) Prepare raw materials of the copper alloy with components shown in Table 1, melt Cu, Ni, Si and Co according to the contents shown in Table 1 to obtain a copper alloy base.

[0044] (2) Obtain multiple copper alloy plates with different textures of the same thickness by directional solidification technology, which are (111), (221), (211), (110), (210), (310) and (100) orientations respectively, and cut the copper alloy plates with different textures into the same size.

[0045] (3) Stack the seven copper alloy plates with different textures in order from hard orientation to soft orientation, i.e. stack them in the order of (111), (221), (211), (110), (210), (310) and (100) textures, to obtain a multi-layer plate with different texture directions stacked in order from hard orientation to soft orientation.

[0046] (4) Perform accumulative roll-bonding on the multi-layer plate, first perform low-temperature rolling at a rolling temperature of 400℃ until the compression amount is 50%, then cut the plate into two equal halves, and stack them together in the repeating order of hard orientation on top and soft orientation on bottom for the next rolling, and so on, wherein the rolling temperature is increased and the rolling compression ratio is decreased for each rolling, and the cycle is repeated 5 times, wherein the rolling temperatures are 400℃, 420℃, 440℃, 460℃ and 480℃ respectively, and the rolling compression ratios are 50%, 40%, 30%, 20% and 10% respectively.

[0047] (5) Annealing heat treatment is performed on the material after accumulative roll-bonding, wherein the annealing temperature is 600℃, the annealing time is 1h, and the cooling mode is furnace natural cooling;

[0048] The tensile strength and electrical conductivity of the high-strength and high-conductivity copper alloy finally obtained are shown in Table 3:

[0049] Table 3 Performance test results of copper alloy of specific embodiment 2 of the present application

[0050] Tensile strength / MPa Electrical conductivity / % IACS 836.7 83.7

[0051] Example 3

[0052] The preparation method of the high-strength and high-conductivity copper alloy described in the present embodiment specifically comprises the following steps:

[0053] (1) Prepare raw materials of the copper alloy with components as shown in Table 1, melt Cu, Ni, Si and Co according to the contents shown in Table 1 to obtain a copper alloy base.

[0054] (2) Obtain multiple copper alloy plates with different textures of the same thickness by directional solidification technology, which are (111), (221), (211), (110), (210), (310) and (100) orientations respectively, and cut the copper alloy plates with different textures into the same size.

[0055] (3) Stack the seven copper alloy plates with different textures in order from hard orientation to soft orientation, i.e. stack them in the order of (111), (221), (211), (110), (210), (310) and (100) textures, to obtain a multi-layer plate with different texture directions stacked in order from hard orientation to soft orientation.

[0056] (4) Perform accumulative roll bonding on the multi-layer plate, first perform low-temperature rolling at a rolling temperature of 400℃ until the compression amount is 50%, then cut the plate into two equal halves, and stack them together in the order of hard orientation on top and soft orientation on bottom, and perform the next rolling, and so on, wherein the rolling temperature is increased and the rolling compression ratio is decreased each time, and the cycle is repeated 4 times, wherein the rolling temperatures are 400℃, 450℃, 500℃ and 550℃, 600℃ respectively, and the rolling compression ratios are 50%, 40%, 30% and 20%, 10% respectively.

[0057] (5) Perform annealing heat treatment on the material after accumulative roll bonding, wherein the annealing temperature is 800℃, the annealing time is 2h, and the cooling method is furnace natural cooling; finally, the tensile strength and electrical conductivity of the high-strength and high-conductivity copper alloy are as shown in Table 4:

[0058] Table 4 Performance test results of copper alloy of specific embodiment 3 of the present application

[0059] Tensile strength / MPa Electrical conductivity / % IACS 866.0 72.9

[0060] Comparative Example 1

[0061] The preparation method of the copper alloy described in the present comparative example specifically comprises the following steps:

[0062] (1) Prepare raw materials of copper alloy with components shown in Table 1, melt Cu, Ni, Si and Co with contents shown in Table 1 to obtain a copper alloy base.

[0063] (2) Obtain copper alloy plates with different textures of the same thickness by directional solidification technology, which are (111), (221), (211), (110), (210), (310) and (100) orientations respectively, and cut the copper alloy plates with different textures into the same size.

[0064] (3) Stack the seven copper alloy plates with different textures in order from hard orientation to soft orientation, i.e. stack them in the order of (111), (221), (211), (110), (210), (310) and (100) textures, to obtain a multi-layer plate with different texture directions stacked in order from hard orientation to soft orientation.

[0065] (4) Perform rolling treatment on the multi-layer plate, with a rolling temperature of 600°C and a rolling compression amount of 80%.

[0066] (5) Perform annealing heat treatment on the material after rolling treatment, with an annealing temperature of 600°C, an annealing time of 1h and a cooling method of furnace natural cooling.

[0067] The tensile strength and electrical conductivity of the copper alloy obtained finally are shown in Table 5:

[0068] Table 5 Performance test results of copper alloy of the specific comparative example 1 of the application

[0069] Tensile strength / MPa Electrical conductivity / % IACS 624.2 68.0

[0070] It can be seen from the comparison that the tensile strength and electrical conductivity of the copper alloy plate after the large compression ratio hot rolling and the cyclic "cold rolling + heat treatment" process are significantly improved.

[0071] Comparative example 2

[0072] The preparation method of the copper alloy of the present comparative example specifically comprises the following steps:

[0073] (1) Prepare raw materials of copper alloy with components shown in Table 1, melt Cu, Ni, Si and Co with contents shown in Table 1 to obtain a copper alloy base.

[0074] (2) Obtain copper alloy plates with different textures of the same thickness by directional solidification technology, which are (111), (221), (211), (110), (210), (310) and (100) orientations respectively, and cut the copper alloy plates with different textures into the same size.

[0075] (2) The multi-layer plate is subjected to accumulative roll bonding treatment, low-temperature rolling is first performed at a rolling temperature of 400 DEG C, and rolling is performed until the compression amount is 50%, then the plate is cut into two equal halves, and the next rolling is performed in the order of hard orientation on top and soft orientation on bottom, and so on, wherein the rolling temperature is increased gradually and the rolling compression ratio is decreased gradually in cycles of 4 times, wherein the rolling temperature is 400 DEG C, 450 DEG C, 500 DEG C and 550 DEG C respectively, and the rolling compression ratio is 50%, 40%, 30% and 20% respectively.

[0076] (3) The material after accumulative roll bonding is subjected to annealing heat treatment, wherein the annealing temperature is 800 DEG C, the annealing time is 2h, and the cooling mode is furnace natural cooling.

[0077] The tensile strength and electrical conductivity of the copper alloy obtained finally are shown in Table 6:

[0078] Table 6 Performance test results of copper alloy of specific comparative example 2 of the present application

[0079] Tensile strength / MPa Electrical conductivity / % IACS 547.5 59.8

[0080] Through the performance test results of the material of comparative example 2 and the material of comparative example 1, it can be found that the stacking of multi-layer texture plate has a very obvious enhancement effect on the tensile strength and electrical conductivity of the copper alloy material, and the accumulative roll bonding process also has a relatively obvious improvement on the tensile strength and electrical conductivity of the material; this is because the microstructure and performance of the heterogeneous texture copper alloy are very different from those of the single copper alloy, and after the accumulative roll bonding, the gradient density twin crystal component is produced in the heterogeneous texture copper alloy due to anisotropy, and the introduction of high-density nanotwin interface in the copper alloy can increase the strength of the copper alloy by one order of magnitude, while maintaining very high electrical conductivity. This is because the size of the twin crystal interface is in the nanometer level, and the scattering effect on electrons is small, so it will not significantly reduce the electrical conductivity of the material; in addition, the gradient nanostructure can effectively suppress strain concentration and realize strain non-localization, and the tensile plasticity is better than that of ordinary coarse-grained structure. The strength of the copper alloy material with gradient nanostructure is twice that of the ordinary coarse-grained copper alloy material.

[0081] In summary, the process method of the present application is convenient to operate, can effectively improve the twin crystal characteristics in the copper alloy substrate, obtain a copper alloy plate with heterogeneous density twin crystal layer, improve the electrical conductivity of the copper alloy under the premise of ensuring that the strength of the copper alloy meets the performance requirements of the alloy, and is suitable for industrial application, and provides a feasible technical solution for the preparation of high-strength and high-conductivity copper alloy materials for aerospace, microelectronic conductive performance components, rail transportation, communication and other industries.

[0082] Finally, it should be understood that the application is not limited to the details of the above-described exemplary embodiments and can be embodied in other specific forms without departing from the spirit or essential characteristics of the application.

Claims

1. A method for obtaining a high-strength high-conductivity copper alloy by preparing a gradient twin, characterized by, The application discloses a method for preparing a copper alloy with high strength and high conductivity by using copper alloy plates with different orientation textures, stacking the plates, and rolling the plates by cumulative roll bonding. The method comprises the following steps: (1) preparing copper alloy plates with different textures, and cutting the plates into copper alloy plates with the same size; (2) stacking the copper alloy plates with different textures in the order of hard orientation to soft orientation to obtain a copper alloy multi-layer plate with different textures stacked in the order of hard orientation to soft orientation; (3) performing cumulative roll bonding on the copper alloy multi-layer plate, i.e. cutting the plate into two halves after each rolling, stacking the two halves in the order of hard orientation on top and soft orientation on the bottom, and performing the next rolling, and repeating the above steps, wherein the rolling temperature is increased gradually, the rolling compression ratio is decreased gradually, and the rolling times are not less than 4; 2. The method of claim 1, wherein the high-strength and high-conductivity copper alloy is obtained by preparing a gradient twin, and the method is characterized by: (4) performing annealing heat treatment on the material after the cumulative roll bonding, and cooling the material in a furnace.

3. The method of claim 1, wherein the gradient twin is formed by: In step (1), the copper alloy plates with different textures are prepared by using directional solidification technology. ​ 4. The method of claim 1, wherein the gradient twin is formed by: In step (3), the rolling temperature is 400-600 DEG C, and the rolling compression ratio is 20-50%. In step (4), the annealing temperature is 500-800 DEG C, and the annealing time is 0.5-2 hours. ​

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