A high-strength, toughness, low-resistivity layered metal and its preparation method

Abstract

The present invention relates to a high-strength, toughness, low-resistivity layered metal and a preparation method thereof. The metal is composed of an alternating large-grain layer and a small-grain layer. The interface between the layers is metallically bonded, and both the large-grain layer and the small-grain layer exhibit a bimodal heterogeneous distribution of grains. The dislocation density inside the grains is extremely low, less than 1.1×10 7 / dm ‑2 d is the grain size. Layered metal materials are produced by alternating current density. The high-speed rotation of the cathode during the electroplating process creates shear stress between the deposited product and the electrolyte, producing a layered metal material with a twinned structure. The twinned layered metal material undergoes recrystallization annealing at a relatively low heating rate. Compared to existing technologies, this invention can produce metal materials with high strength, toughness, and low resistivity.

Description

Technical Field

[0001] The present invention belongs to the fields of material science and engineering and electrical engineering, and in particular relates to a metal material with high strength, toughness and electrical conductivity and a preparation method thereof. Background Art

[0002] In industrial applications, the strength, plasticity and conductivity of metal materials are three crucial properties. For example, the wires in the conductive magnet coils are subjected to huge electromagnetic forces and also need to have low resistivity. The electrical connection leads (also called bonding wires) between the chip and the external circuit need to have certain strength and plasticity while also having excellent electrical conductivity. However, conventional high-conductivity materials often have low strength, such as Cu, Ag, Au, Ni, etc. However, increasing their strength through various material strengthening mechanisms (such as solid solution strengthening, dislocation strengthening, grain refinement, precipitation phases, etc.) will lead to a significant increase in their resistivity and a decrease in plasticity. This is because these strengthening mechanisms often introduce a large number of defects (point defects, line defects and surface defects) into the material. The presence of these defects will significantly increase the scattering effect on electrons, thereby reducing the material's electrical conductivity, and will also inhibit the interaction of dislocations and reduce the material's plasticity. For example, adding one or more other elements to pure Cu to form a copper alloy increases the strength of pure Cu by 2-3 times, but also causes its electrical conductivity to drop to 10%-40% of pure Cu, and its plasticity is also reduced (Reference 1: Shen Yongfeng, Lu Lei, Chen Xianhua, Qian Lihua, Lu Ke, Strength and conductivity of nanotwinned pure Cu, Physics, 344-347, 05 (2005)). Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art by providing a high-strength, low-resistivity layered metal and a method for its preparation. The metal is a low-dislocation-density structural material with a layered structure and a bimodal grain size distribution. The present invention proposes a preparation method that both improves the material's strength and toughness while maintaining low resistivity. This method utilizes a high-speed cathode rotation electrodeposition method and a slow-heating heat treatment method to produce the high-strength, low-resistivity layered metal. This method is low-cost, and the coating thickness and structure are controllable, making it suitable for large-scale production and promising industrial applications.

[0004] The object of the present invention can be achieved by the following technical solution: a high-strength, toughness, low-resistivity layered metal, which is composed of a layer of large grains and a layer of small grains alternatingly, with metallic bonds between the layer interfaces, and a heterogeneous distribution of bimodal grains in both the large grain layer and the small grain layer, and an extremely low dislocation density within the grains, less than 1.1×10 7 / dm -2 , d is the grain size.

[0005] Furthermore, the average grain size of the large grain layer is 2.0 μm to 5.0 μm;

[0006] The average grain size of the small grain layer is 500nm-1.8μm.

[0007] The present invention also provides a method for preparing a high-strength, toughness, and low-resistivity layered metal, the method comprising the following steps:

[0008] (1) Select the target deposition product and configure the corresponding electroplating solution according to the needs of the working service environment;

[0009] (2) Based on the service environment of the workpiece and taking into account the strength and plasticity, the thickness of each layer and the corresponding current density are designed, and then the electrodeposition time of each layer is calculated according to Faraday's law (m = Vρ = 1.095 × alt, where m, v and ρ are the mass, volume and density of the specific layer, a is the current efficiency, I is the current, and t is the electrodeposition time) to achieve a layered structure. The electroplating method is used to deposit the electroplated layer layer by layer on the cathode surface. During the electrodeposition process, the cathode is in a high-speed rotating state so that shear stress exists between the cathode deposition product and the solution, so that a high-density nano-twin structure is generated in the deposition product;

[0010] (3) The deposited product is recrystallized and annealed at a low heating rate, so that the incoherent nano-twin boundaries in the electrodeposited product gradually become coherent through the grain boundary relaxation process, reducing the grain boundary energy to stabilize the electrodeposited product. During the subsequent heat treatment of the material, the stable grain boundaries inhibit the grain coarsening behavior, while the fine grains are conducive to the dislocation climbing to the grain boundary or the sample surface to produce annihilation, thereby obtaining a low dislocation density structure and activating the limited dislocation source strengthening and toughening mechanism. During the electrodeposition process, the stirrer connected to the cathode rotates at a high speed, and the contact resistance of the carbon brush inside it changes continuously, causing some grains to nucleate and grow at a higher overpotential. These grains with higher nucleation energy grow abnormally in the subsequent annealing, resulting in a size distribution of large and small grains in each layer of the electroplated product, that is, a bimodal structure. Under the action of the bimodal and layered heterogeneous structure and the limited dislocation source mechanism caused by the low dislocation density, a metal material with high strength, toughness and low resistivity is finally achieved.

[0011] Furthermore, the electroplating solution is one of a Cu electroplating solution, a Ni electroplating solution, an Ag electroplating solution or an Au electroplating solution.

[0012] Furthermore, the current density of the electroplated Cu is 0.05–0.8 mA / mm 2 The current density of Ni electroplating is 0.05–0.85 mA / mm 2, the current density of Ag electroplating is 0.01–0.4 mA / mm 2 , the current density of Au electroplating is 0.01–1 mA / mm 2 .

[0013] Furthermore, during the electrodeposition process, the thickness of each layer is controlled to be 5-2000 μm, and the current density of the large grain layer is 3-10 times that of the small grain layer.

[0014] Furthermore, the cathode is connected to a stirrer so that the cathode rotation speed is 150-3000 rpm.

[0015] Furthermore, the heating rate of the recrystallization annealing is 0.1-5°C / min, the heat treatment temperature is between 200°C and 100°C lower than the melting point of the metal material, and after the heat treatment temperature is raised to the set temperature, the heat treatment holding time is between 30min-5h.

[0016] Furthermore, the cooling method of the recrystallization annealing is one of air cooling, furnace cooling, water quenching or oil quenching.

[0017] Furthermore, the number of electroplating layers deposited on the cathode surface is not less than 6 layers.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The material prepared by the present invention has a unique microstructure, consisting of a layer of alternating large grains and a layer of small grains. The interface between the layers is metallically bonded and has strong bonding ability. In addition, both the large grain layer and the small grain layer show a bimodal heterogeneous distribution of grains. The dislocation density within the grains is extremely low, less than 1.1×107 / d m-2, where d is the grain size in meters. The low dislocation density can activate the finite dislocation source mechanism. Under the combined action of the heterogeneous and finite dislocation source mechanisms, the material has high strength and toughness. In addition, due to its low intracrystalline dislocation density, its electron scattering ability is far lower than that of materials of the same strength, and therefore the material also has very good conductivity.

[0020] 2. The material prepared by the present invention has strong applicability. The layered material with a bimodal grain size distribution prepared in the present invention has high toughness and electrical conductivity. Therefore, this material can be widely used in the electrical industry, computer industry and wireless communication industry.

[0021] 3. The preparation method of the present invention is simple and adopts traditional electroplating technology. It only needs to improve the cathode movement state and adopt appropriate electrodeposition and heat treatment parameters to obtain a high-strength, toughness and low-resistivity metal material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram illustrating the electrodeposition apparatus in Example 1;

[0023] In the figure, 1 – cathode mixer and its bracket, 2 – constant temperature magnetic stirrer, 3 – power supply, 4 – acrylic constant temperature water bath, 5 – beaker, 6 – temperature sensor, 7 – cathode metal bracket, 8 – Ni wire, 9 – cathode glass fiber bracket, 10 – magnetic stirring rotor, 11 – anode pure Ni plate, 12 – anode wire, 13 – cathode wire;

[0024] Figure 2 This is the file (a) that needs to import the output power current and time in Example 1, and (b) the current change diagram. CH1.SL represents the current of one channel (in A), T1 represents the execution time of the corresponding current of channel 1 (in seconds), and CH2.SL and T2 represent the current and execution time of two channels.

[0025] Figure 3 (a) EBSD diagram of the layered Ni after annealing, showing the bimodal grain size distribution of the electrodeposited Ni in Example 1; (b) grain size distribution diagrams of the Ni as a whole, the large grain layer, and the small grain layer, respectively;

[0026] Figure 4 To characterize the uniaxial tensile curve in Example 1, the uniaxial tensile curve and resistivity of a commercial cold-rolled pure Ni plate (grain size 2 μm) are also included;

[0027] Figure 5 Schematic diagram of the structure of the cathode glass fiber support 9;

[0028] Figure 6 Schematic diagram of the structure of the cathode support 7. DETAILED DESCRIPTION

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] The electroplating method of the high-strength, toughness, and low-resistivity layered metal material of the present invention utilizes an alternating current density to achieve the preparation of the layered metal material. During the electroplating process, the cathode rotates at high speed, and shear stress exists between the deposited product and the electrolyte, thereby preparing a layered metal material with a twin structure. Due to the continuous change in the contact resistance of the carbon brush in the cathode mixer in the circuit, some grains nucleate and grow at a higher overpotential. After the twinned layered metal material is subjected to recrystallization annealing at a low heating rate, the incoherent twin boundaries in the deposited sample will first gradually become coherent, stabilizing the material. During the subsequent heat treatment process, the coherent twin structure inhibits grain coarsening, and the fine grains are conducive to dislocation annihilation to produce a low dislocation density structure and introduce a finite dislocation source toughening mechanism. Grains with higher nucleation energy will grow abnormally, resulting in a bimodal grain size distribution within the lamellar structure. Under the action of the bimodal and layered heterogeneous structure and the finite dislocation source mechanism, a metal material with high strength, toughness, and low resistivity is achieved.

[0031] Example 1

[0032] Rod-shaped high-strength and tough metal Ni materials are prepared using electrodeposition technology, which are suitable for high temperature, alkaline and non-oxidizing acid environments.

[0033] 1) According to Figure 1 An experimental device was constructed, including a cathode mixer and its bracket 1, a constant temperature magnetic stirrer 2, a power supply 3, an acrylic constant temperature water bath 4, a beaker 5, a temperature sensor 6, a cathode stainless steel bracket 7, a Ni wire 8, a cathode glass fiber bracket 9, a magnetic stirring rotor 10, an anode pure Ni plate 11, an anode wire 12, and a cathode wire 13; wherein the cathode mixer is connected to the cathode bracket 7, and a cathode is provided under the cathode bracket 7. In this embodiment, the cathode is a Ni wire 8 (i.e., a deposition substrate) 8, and the Ni wire 8 is located in the beaker 5. The beaker 5 is placed in the acrylic constant temperature water bath 4, and the acrylic constant temperature water bath 4 is provided with a temperature sensor 6. The cathode glass fiber bracket 9 is fixed to the cathode bracket 7 by acrylic screws (see Figure 5-6 ), Ni wire 8 is first fixed to cathode fiberglass support 9 with acrylic screws. The upper end of Ni wire 8 extends and connects to cathode stainless steel support 7 to form a passage. A magnetic stirring rotor 10 is installed at the bottom of beaker 5. A pure Ni anode plate 11 is also located inside beaker 5. This pure Ni anode plate 11 is connected to power supply 3 via anode wire 12, and the cathode stirrer is connected to power supply 3 via cathode wire 13. Beaker 5 contains electrolyte.

[0034] The electrolyte raw materials are chemically pure nickel sulfamate (300 g / L), boric acid (40 g / L), nickel chloride (15 g / L), and sodium dodecyl sulfate (0.1 g / L). Ultrapure water is added to prepare 1 L of electrolyte, the solution pH = 4.0, the temperature is 50°C, and the distance between the anode and cathode is 10 cm.

[0035] 2) The cathode is a Ni wire with a diameter of 25 μm, the anode is electrolytic pure Ni, and the cathode and anode area ratio is 1:600.

[0036] 3) Using the cathode Ni wire 8 as the deposition substrate, a large grain layer and a small grain layer are deposited layer by layer on its surface to form an alternating structure of a large grain layer and a small grain layer. When depositing the large grain layer, the current density is controlled to be 0.4 mA / mm 2 When depositing the small grain layer, the current density is controlled to be 0.1 mA / mm 2 During the deposition process, the cathode speed was controlled at 800 rpm. The time for each layer was calculated using Faraday's law (m = Vρ = 1.095 × alt, where m, v, and ρ are the mass, volume, and density of the specific layer, a is the current efficiency, I is the current, and t is the electrodeposition time). The calculated time and corresponding current were imported into the output power supply in text form (see Figure 2 ). 20 layers were deposited in total, and the current density of the 20th layer was 0.4 mA / mm 2 , so that the 20th layer has a large-grain structure.

[0037] 4) The prepared rod-shaped sample was vacuum annealed, that is, the sample was placed in a vacuum heating furnace and heated to 700℃ at a rate of 2℃ / min, kept at 700℃ for 1 hour, and cooled in the furnace. The microstructure and grain size distribution of the prepared pure Ni rod are shown in Figure 3 .like Figure 3 As shown, the thickness of each layer is about 16 μm, and both the large grain layer and the small grain layer show a double peak structure (see Figure 3 (b)). Among them, the average grain size of the small grain layer is 535nm and 1.6μm, the average grain size of the large grain layer is 2.2μm and 4.3μm, and the area-weighted average grain size of the entire material is 1.95μm. Chemical analysis results show that the purity of the prepared Ni sample is about 99.97%, and the chemical composition content of small impurities is shown in the following table (unit is wt.ppm)

[0038] Co Cu Fe Pb Cd Mg Mn 71.4 40.5 50.7 59.8 0.6 ＜0.8 3.1 Pd Sb Si Sn Zn C S 8.3 ＜0.5 ＜0.1 46.9 4.7 15.9 14.7

[0039] The density of pure Ni measured by Archimedes' principle is 8.901±0.008g / cm 3 , equivalent to 99.92% of the theoretical density of metallurgical pure Ni. Figure 4 The uniaxial tensile curve of the Ni rod shows the presence of a yield point phenomenon and strain hardening behavior, indicating that Ni has a finite dislocation source toughening mechanism. The yield strength of the material at room temperature is 601 MPa, the uniform elongation is 27.4%, and the electrical conductivity measured by the four-electrode method is 7.1×10 6S / m. Its yield strength is 452 MPa higher than that of commercial cold-rolled pure nickel with a similar grain size (2 μm), its uniform elongation is 6% higher, and its electrical conductivity is 1.8 times that of commercial cold-rolled pure nickel. Due to the large grain structure with low dislocation density in the outermost layer and the pronounced "skin effect" of alternating current, this material exhibits excellent alternating current conductivity in addition to its excellent direct current conductivity.

[0040] Example 2

[0041] Plate-shaped, high-strength, and high-toughness pure Ni with equal layer thickness is prepared using electrodeposition technology.

[0042] 1) The electrolyte raw materials are chemically pure nickel sulfate (275 g / L), boric acid (40 g / L), nickel chloride (25 g / L), and sodium dodecyl sulfate (0.1 g / L). Ultrapure water is added to prepare 1 L of electrolyte. The solution pH is 3.6, the temperature is 43 ° C, and the distance between the anode and cathode is maintained at 10 cm.

[0043] 2) The cathode is 316L stainless steel plate, the anode is electrolytic pure Ni, and the cathode and anode area ratio is 1:10.

[0044] 3) Current density is 0.5 mA / mm 2 and 0.1mA / mm 2 , 0.5mA / mm 2 The current density layer is electroplated for 12 minutes per layer, 0.1 mA / mm 2 The electroplating time of each current density layer is 60min, and 32 layers are deposited in total. The current density of the 32nd layer is 0.5mA / mm 2 , the cathode speed is 800rpm.

[0045] 4) The prepared plate sample was mechanically peeled off from the 316L stainless steel substrate, and then annealed in an atmospheric atmosphere, kept at 600℃ for 1h, with an annealing heating rate of 2℃ / min, and cooled in the furnace. A high-strength and tough layered pure Ni material was prepared, each layer was about 26μm thick, and both the large grain layer and the small grain layer showed a bimodal structure. Among them, the average grain size of the small grain layer was 1.6μm and 3.9μm, and the average grain size of the large grain layer was 6.5μm and 10.6μm. The yield strength of the material at room temperature is (420MPa), the uniform elongation is (32.8%), and the conductivity measured by the four-electrode method is 8.2×10 6 S / m.

[0046] Example 3

[0047] Plate-shaped, high-strength and tough bimodal grain-sized layered metal Cu materials were prepared using electrodeposition technology.

[0048] 1) The electrolyte raw materials are analytical grade copper sulfate (220 g / L) and high-grade concentrated sulfuric acid (50 g / L). Ultrapure water is added to prepare 1 L of electrolyte, pH = 0.7, and electrodeposition is performed at room temperature with a distance of 10 cm between the anode and cathode.

[0049] 2) The cathode is a pure titanium plate, the anode is electrolytic pure Cu, and the anode and cathode area ratio is 1:10.

[0050] 3) The current density used is 0.5 mA / mm 2 and 0.1mA / mm 2 , respectively, to prepare large grain layer and small grain layer, 0.5mA / mm 2 The current density of deposition was 0.1 mA / mm for 12 minutes. 2 The current density was 0.6 mA / mm for 60 minutes, and 32 layers were deposited. The current density of the 32nd layer was 0.6 mA / mm 2 , the cathode speed is 500rpm.

[0051] 4) The prepared plate sample was mechanically peeled off from the titanium plate and then annealed in an atmospheric atmosphere, kept at 400°C for 1 hour, with a heating rate of 1°C / min and air cooling. A high-strength and tough layered pure Cu material was prepared, each layer was about 28μm thick, and both the large grain layer and the small grain layer showed a bimodal structure. Among them, the average grain size of the small grain layer was 3.6μm and 5.2μm, and the average grain size of the large grain layer was 6.7μm and 10.8μm. The yield strength of the material at room temperature is (362MPa), the uniform elongation is (15.6%), and the conductivity measured by the four-electrode method is 3.2×10 7 S / m.

[0052] Example 4

[0053] Plate-shaped high-strength and high-toughness metal Cu material is prepared using electrodeposition technology.

[0054] 1) The electrolyte raw materials are analytical grade copper pyrophosphate (60 g / L), potassium pyrophosphate (280 g / L), and ammonium citrate (20 g / L). Ultrapure water is added to prepare 1 L of electrolyte, pH = 8.2, electrolysis temperature is 45 ° C, and the distance between the anode and cathode is 10 cm.

[0055] 2) The cathode material is a gold-plated tungsten wire with a diameter of 25 μm, the anode material is electrolytic pure Cu, and the cathode-cathode ratio is 1:600.

[0056] 3) Current density 0.3mA / mm 2 and 0.1mA / mm 2 To prepare large grain layer and small grain layer respectively, 0.1mA mA / mm 2 The current density of deposition was 0.3 mA / mm for 30 minutes.2 The current density was 0.3 mA / mm for 10 minutes, and 20 layers were deposited. The current density of 10 layers was 0.3 mA / mm 2 , the cathode speed is 500rpm.

[0057] 4) The prepared rod-shaped sample was vacuum annealed at 400°C for 1 hour with a heating rate of 1°C / min and furnace cooling. A layered pure Cu material with high strength and toughness and a bimodal grain size distribution was prepared. The thickness of each layer was about 12 μm, and both the large grain layer and the small grain layer showed a bimodal structure. Among them, the average grain size of the small grain layer was 0.45 μm and 1.7 μm, and the average grain size of the large grain layer was 1.8 μm and 3.5 μm. The yield strength of the material at room temperature was (406 MPa), the uniform elongation was (11.5%), and the conductivity measured by the four-electrode method was 2.2×10 7 S / m.

[0058] Example 5

[0059] High strength and toughness metallic Ag thin films were prepared using electrodeposition technology.

[0060] 1) The electrolyte raw materials are analytical grade silver nitrate (50 g / L), ammonium thiosulfate (200 g / L), ammonium acetate (25 g / L), and anhydrous sodium sulfite (90 g / L). Ultrapure water is added to prepare 500 mL of electrolyte, pH = 5.5, the electrolysis temperature is 30 ° C, and the distance between the anode and cathode is 7 cm.

[0061] 2) The cathode material is a polished stainless steel plate, the anode material is a pure Ag sheet, and the cathode-cathode ratio is 1:5.

[0062] 3) Current density 0.1mA / mm 2 and 0.02mA / mm 2 To prepare large grain layer and small grain layer respectively, 0.1mA mA / mm 2 The current density of deposition was 0.02 mA / mm for 5 minutes. 2 The current density was 0.1 mA / mm for 25 minutes, and 10 layers were deposited. The current density of the 10th layer was 0.1 mA / mm 2 , the cathode speed is 500rpm.

[0063] 4) The prepared rod-shaped sample was vacuum annealed at 300°C for 1 hour with a heating rate of 0.5°C / min and furnace cooling. A layered pure Ag material with high strength and toughness and a bimodal grain size distribution was prepared. The thickness of each layer was about 2μm, and both the large grain layer and the small grain layer showed a bimodal structure. Among them, the average grain size of the small grain layer was 0.12μm and 0.26μm, and the average grain size of the large grain layer was 0.57μm and 0.96μm. The yield strength of the material at room temperature was (296MPa), the uniform elongation was (15%), and the conductivity measured by the four-electrode method was 1.7×10 7 S / m.

[0064] Example 6

[0065] High-strength and tough metal Au films are prepared using electrodeposition technology.

[0066] 1) The electrolyte raw materials are analytical grade gold chloride (25 g / L), sodium sulfite (110 g / L), ammonium citrate (70 g / L), and cobalt sulfate (0.5 g / L). Ultrapure water is added to prepare 200 mL of electrolyte, pH = 6, electrolysis temperature is 25 ° C, and the distance between the anode and cathode is 5 cm.

[0067] 2) The cathode material is a polished stainless steel plate, the anode material is a pure Au sheet, and the cathode-cathode ratio is 1:5.

[0068] 3) Current density 0.08mA / mm 2 and 0.02mA / mm 2 To prepare large grain layer and small grain layer respectively, 0.02mAmA / mm 2 The current density of deposition was 0.08 mA / mm for 8 minutes. 2 The current density was 0.08 mA / mm for 1 minute, and 10 layers were deposited. The current density of the 10th layer was 0.08 mA / mm 2 , the cathode speed is 500rpm.

[0069] 4) The prepared rod-shaped sample was vacuum annealed at 300°C for 1 hour with a heating rate of 0.5°C / min and furnace cooling. A layered pure Au film with high strength and toughness and a bimodal grain size distribution was prepared. The thickness of each layer was about 1.5μm, and both the large grain layer and the small grain layer showed a bimodal structure. Among them, the average grain size of the small grain layer was 0.1μm and 0.18μm, and the average grain size of the large grain layer was 0.38μm and 0.55μm. The yield strength of the material at room temperature was (327MPa), the uniform elongation was (22%), and the conductivity measured by the four-electrode method was 2.6×10 7 S / m.

[0070] The above describes the embodiments of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principles of the technical solution of the present invention should be equivalent replacement methods. As long as they comply with the purpose of the invention and do not deviate from the technical principles and inventive concepts of the present invention, they belong to the scope of protection of the present invention.

Claims

1. A high-strength, toughness, low-resistivity layered metal, characterized in that: The metal is composed of an alternating layer of large grains and a layer of small grains. The interface between the layers is metallically bonded, and both the large grain layer and the small grain layer show a bimodal heterogeneous distribution of grains. The dislocation density inside the grains is extremely low, less than 1.1 × 10 7 / dm -2 , d is the grain size; The average grain size of the large grain layer is 2.0 μm to 5.0 μm; The average grain size of the small grain layer is 500 nm to 1.8 μm; The metal is prepared by the following method: (1) Select the target deposition product and configure the corresponding electroplating solution according to the needs of the working service environment; (2) Designing the thickness of each layer and the corresponding current density, and then calculating the electrodeposition time of each layer according to Faraday's law, using an electroplating method to deposit the electroplated layer layer by layer on the cathode surface. During the electrodeposition process, the cathode is in a high-speed rotating state so that shear stress exists between the cathode deposition product and the solution, so that a high-density nano-twin structure is generated in the deposition product; the cathode is connected to a stirrer so that the cathode rotation speed is 150-3000 rpm; (3) The deposited product is subjected to recrystallization annealing, wherein the recrystallization annealing has a heating rate of 0.1-5 °C / min, the heat treatment temperature is between 200 °C and 100 °C lower than the melting point of the metal material, and after the heat treatment temperature is raised to the set temperature, the heat treatment holding time is between 30 min-5 h, so that the incoherent nano-twin boundaries in the electrodeposited product are gradually coherent through the grain boundary relaxation process, thereby reducing the grain boundary energy to stabilize the electrodeposited product.

2. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 1, characterized in that: The method comprises the following steps: (1) Select the target deposition product and configure the corresponding electroplating solution according to the needs of the working service environment; (2) Design the thickness of each layer and the corresponding current density, and then calculate the electrodeposition time of each layer according to Faraday's law. Use the electroplating method to deposit the electroplated layer layer by layer on the cathode surface. During the electrodeposition process, the cathode is in a high-speed rotation state so that shear stress exists between the cathode deposition product and the solution, so that a high-density nano-twin structure is generated in the deposition product; (3) The deposited product is recrystallized and annealed, so that the incoherent nano-twin boundaries in the electrodeposited product gradually become coherent through the grain boundary relaxation process, thereby reducing the grain boundary energy and stabilizing the electrodeposited product.

3. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 2, characterized in that: The electroplating solution is one of Cu electroplating solution, Ni electroplating solution, Ag electroplating solution or Au electroplating solution.

4. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 3, characterized in that: The current density of the electroplated Cu is 0.05 – 0.8 mA / mm 2 , the current density of Ni electroplating is 0.05 – 0.85 mA / mm 2 , the current density of Ag electroplating is 0.01 – 0.4 mA / mm 2 The current density of Au electroplating is 0.01 – 1 mA / mm 2 .

5. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 2, characterized in that: During the electrodeposition process, the thickness of each layer is controlled at 5-2000 μm, and the current density of the large grain layer is 3-10 times that of the small grain layer.

6. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 2, characterized in that: The cathode is connected to a stirrer so that the cathode rotation speed is 150-3000 rpm.

7. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 2, characterized in that: The heating rate of the recrystallization annealing is 0.1-5°C / min, the heat treatment temperature is between 200°C and 100°C lower than the melting point of the metal material, and after the heat treatment temperature is raised to the set temperature, the heat treatment holding time is between 30 min-5 h.

8. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 2, characterized in that: The cooling method of the recrystallization annealing is one of air cooling, furnace cooling, water quenching or oil quenching.

9. The method for preparing a high-strength, toughness, low-resistivity layered metal according to claim 2, characterized in that: The number of electroplating layers deposited on the cathode surface is not less than 6 layers.

Images