A method for manufacturing a copper alloy having a dual heterostructure

Abstract

The application discloses a preparation method of a copper alloy with a double heterostructure and belongs to the technical field of material preparation. The method comprises the following steps: firstly, a copper plate and an aluminum plate are subjected to accumulative roll bonding to obtain a Cu / Al multilayer composite plate; and finally, the obtained sample is subjected to surface grinding and polishing, and surface nanocrystallization treatment is carried out at room temperature for 2 min. It is found for the first time that after the accumulative roll bonding, annealing is carried out, a hetero-layer structure is formed, and the traditional surface nanocrystallization structure is superposed, so that a double heterostructure is formed, and the double heterostructure with matched yield strength and plasticity is obtained.

Description

Technical Field

[0001] This invention relates to a method for preparing a copper alloy with a dual heterostructure, belonging to the field of materials preparation technology. Background Technology

[0002] With the development of industries such as aerospace and automobiles, the demand for high-strength and high-ductility materials is becoming increasingly urgent. Strength and ductility are key elements in determining the performance of metallic materials. In the development process, high strength and extremely low plasticity often occur simultaneously, which is what we often call an inverted relationship. Traditional Cu / Al multilayer composite plates are frequently used in industrial production due to their low price and good processing performance. However, their extremely low yield strength limits their development. Using large plastic deformation sacrifices plasticity to increase strength, failing to achieve a good balance between strength and plasticity. Cu / Al multilayer composite plates produced by cumulative rolling have high yield strength but are accompanied by low plasticity. Long-term high-temperature annealing greatly reduces strength while increasing elongation, also failing to achieve a good balance between strength and plasticity.

[0003] Therefore, there is an urgent need to develop a preparation method that can improve the strength of Cu / Al multilayer composite plates without reducing their plasticity. Summary of the Invention

[0004] To address the problems existing in current Cu / Al multilayer composite plates, this invention provides a method for preparing a copper alloy with a dual heterostructure. The Cu / Al multilayer composite plate, after cumulative rolling, is first annealed to increase internal grain size, and then surface nano-sizing is used to create a gradient grain size structure, optimizing its mechanical properties. The specific preparation steps are as follows:

[0005] (1) First, the pure aluminum plate and the pure copper plate are homogenized and annealed, and the oxide film and other impurities on the surface of the original plate are removed with acetone and an angle grinder.

[0006] (2) Stack the pure copper plate and pure aluminum plate processed in step (1) together and rivet the two plates together.

[0007] (3) The riveted copper and aluminum plates are rolled to obtain Cu / Al multilayer composite plates.

[0008] (4) The rolled Cu / Al multilayer composite plate was annealed at 350℃ for 10 min.

[0009] (5) The surface of the Cu / Al multilayer composite plate after annealing is polished and the surface of the Cu / Al multilayer composite plate is nano-sized at room temperature to finally obtain a Cu / Al multilayer composite plate with dual heterostructure.

[0010] Preferably, the pure aluminum plate and pure copper plate in step (1) are commercial plates.

[0011] Preferably, in step (1), the annealing temperature of the pure aluminum plate is 370°C, the time is 2 hours, and it is furnace cooled; the annealing temperature of the pure copper plate is 500°C, the time is 2 hours, and it is furnace cooled.

[0012] Preferably, in step (3), no preheating or lubrication is performed during the rolling process, and air cooling is used after rolling. The reduction rate is 50% each time, and a total of 8 passes of cumulative rolling are performed.

[0013] Preferably, the surface nano-treatment in step (4) is carried out in a high-energy ball mill with a test frequency of 50 Hz, 208 steel balls with a diameter of 8 mm, and a treatment time of 2 min.

[0014] Beneficial effects of the present invention

[0015] (1) This invention uses cumulative rolling and combined with surface nano-sizing technology to bombard the surface of Cu / Al multilayer composite plate with steel balls at high speed to prepare a dual heterogeneous Cu / Al multilayer composite plate with heterogeneous layered structure and gradient structure. Its comprehensive mechanical properties are greatly improved compared with cumulative rolling, and the plasticity of the material is greatly improved while ensuring yield strength.

[0016] (2) This invention is the first to discover that after annealing, the grain structure is a layered structure and gradually increases from the surface to the core, resulting in a Cu / Al multilayer composite plate with a dual heterostructure.

[0017] (3) During the tensile test, the synergy between the heterogeneous layered structure and the gradient structure grains, as well as the combination of multiple deformation mechanisms, improve the comprehensive mechanical properties of the copper alloy, reducing the yield strength slightly while maintaining good plasticity.

[0018] (4) The process of this invention is simple, low-cost, and easy to implement in industrial production, which greatly improves the application range of copper alloys. Detailed Implementation

[0019] The present invention will be further described in detail below with specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0020] Example 1

[0021] A method for preparing a copper alloy with a dual heterostructure, the specific preparation steps of which are as follows:

[0022] (1) First, the cold-rolled pure aluminum plate and pure copper plate are homogenized and annealed. The annealing temperature of the pure aluminum plate is 370℃ and the time is 2h, and it is furnace cooled. The annealing temperature of the pure copper plate is 500℃ and the time is 2h, and it is furnace cooled. The oxide film and other impurities on the surface of the original plate are removed with acetone and an angle grinder.

[0023] (2) Stack the pure copper plate and pure aluminum plate processed in step (1) together, drill holes at the four corners of the plates, and rivet the two plates together.

[0024] (3) The riveted copper and aluminum plates are rolled without preheating or lubrication during the rolling process. After rolling, air cooling is used. The reduction rate is 50% each time, and a total of 8 passes of cumulative rolling are performed.

[0025] (4) After removing the impurities from the surface of the rolled Cu / Al multilayer composite plate, it is annealed at 350℃ for 10 minutes.

[0026] (5) The surface of the Cu / Al multilayer composite plate after annealing is polished and the polished Cu / Al multilayer composite plate is placed in a high-energy ball mill for surface nano-processing. The test frequency is 50Hz, the number of steel balls is 208, the diameter is 8mm, and the processing time is 2min. Finally, a Cu / Al multilayer composite plate with dual heterostructure is obtained.

[0027] Comparative Example 1

[0028] In comparison, in this example, the material was annealed at 200°C for 10 minutes after the cumulative rolling process. The specific preparation steps are as follows:

[0029] (1) First, the cold-rolled pure aluminum plate and pure copper plate are homogenized and annealed. The annealing temperature of the pure aluminum plate is 370℃ and the time is 2h, and it is furnace cooled. The annealing temperature of the pure copper plate is 500℃ and the time is 2h, and it is furnace cooled. The oxide film and other impurities on the surface of the original plate are removed with acetone and an angle grinder.

[0030] (2) Stack the pure copper plate and pure aluminum plate processed in step (1) together, drill holes at the four corners of the plates, and rivet the two plates together.

[0031] (3) The riveted copper and aluminum plates are rolled without preheating or lubrication during the rolling process. After rolling, air cooling is used. The reduction rate is 50% each time, and a total of 8 passes of cumulative rolling are performed.

[0032] (4) After removing the impurities from the surface of the rolled Cu / Al multilayer composite plate, it is annealed at 200℃ for 10 minutes.

[0033] (5) The surface of the Cu / Al multilayer composite plate after annealing is polished and the polished Cu / Al multilayer composite plate is placed in a high-energy ball mill for surface nano-processing. The test frequency is 50Hz, the number of steel balls is 208, the diameter is 8mm, and the processing time is 2min. Finally, the Cu / Al multilayer composite plate is obtained.

[0034] Comparative Example 2

[0035] In contrast, this embodiment differs from Embodiment 1 in that the surface of the Cu / Al multilayer composite plate material is not nano-sized. The specific preparation steps are as follows:

[0036] (1) First, the cold-rolled pure aluminum plate and pure copper plate are homogenized and annealed. The annealing temperature of the pure aluminum plate is 370℃ and the time is 2h, and it is furnace cooled. The annealing temperature of the pure copper plate is 500℃ and the time is 2h, and it is furnace cooled. The oxide film and other impurities on the surface of the original plate are removed with acetone and an angle grinder.

[0037] (2) The surface-treated copper and aluminum plates are stacked together and holes are drilled at the four corners of the plates. The two plates are riveted together and rolled. No preheating or lubrication is performed during the rolling process. After rolling, air cooling is used. The reduction rate is 50% each time, and a total of 6 passes of cumulative stacking rolling are performed.

[0038] (3) After removing the impurities from the surface of the cold-rolled sample (Cu / Al multilayer composite board), Cu / Al multilayer composite board material is obtained. Then, the board is annealed at 350℃ for 10 minutes to finally obtain Cu / Al multilayer composite board.

[0039] Comparative Example 3

[0040] In contrast, this embodiment differs from Embodiment 2 in that the Cu / Al multilayer composite plate material is not subjected to surface nano-sizing treatment, and the cumulative rolling process is changed to three times. The specific preparation steps are as follows:

[0041] (1) First, the cold-rolled pure aluminum plate and pure copper plate are homogenized and annealed. The annealing temperature of the pure aluminum plate is 370℃ and the time is 2h, and it is furnace cooled. The annealing temperature of the pure copper plate is 500℃ and the time is 2h, and it is furnace cooled. The oxide film and other impurities on the surface of the original plate are removed with acetone and an angle grinder.

[0042] (2) The surface-treated copper and aluminum plates are stacked together and holes are drilled at the four corners of the plates. The two plates are riveted together and rolled. No preheating or lubrication is performed during the rolling process. After rolling, air cooling is used. The reduction rate is 50% each time, and a total of 3 passes of cumulative stacking rolling are performed.

[0043] (3) After removing the impurities from the surface of the cold-rolled sample (Cu / Al multilayer composite plate), anneal it at 350°C for 10 min to obtain Cu / Al multilayer composite plate material.

[0044] The copper alloy materials obtained in Example 1 and Comparative Examples 1-3 were subjected to performance tests, and the results are shown in Table 1.

[0045] Table 1 shows the performance test results of the copper alloy materials obtained in Examples 1-2 and Comparative Examples 1-3.

[0046] Yield strength (MPa) Ultimate tensile strength (MPa) Uniform elongation (%) Example 1 295 330 18.8 Comparative Example 1 380 400 1 Comparative Example 2 280 289 10.3 Comparative Example 3 186 253 8.6

[0047] As can be seen from the table, the full annealing step was omitted in the preparation process of Comparative Example 1 compared with Example 1. Although the copper alloy material prepared in Comparative Example 1 has a high yield strength, its elongation is extremely low. This is because annealing at 200℃ for 10 minutes cannot transform the elongated deformed grains in the internal structure into recrystallized grains. The deformed grains have a high dislocation density and low plasticity.

[0048] As can be seen from the table, the surface nano-sizing step was omitted in the preparation process of Comparative Example 2 compared with Example 1. The yield strength of the copper-aluminum alloy material prepared in Example 1 is basically the same as that of Comparative Example 2, but the elongation is 8% different. The reason is the synergy between the heterogeneous layered structure and the gradient structure grains. The gradient structure formed by the nanocrystals and coarse grains brings a good toughening effect to Example 1.

[0049] As can be seen from the table, the number of cumulative rolling steps was reduced in Comparative Example 3 compared to Example 1. The copper alloy material prepared in Comparative Example 3 has relatively poor yield strength and very poor elongation. This is because after the number of cumulative rolling steps is reduced, the bonding between the pure copper plate and the pure aluminum plate becomes worse. During the stretching process, it is easy to break at the bonding point, resulting in a decrease in uniform elongation.

[0050] The comparison shows that the Cu / Al multilayer composite plate obtained through cumulative rolling transforms the grain structure into a heterogeneous layered structure. Furthermore, under surface mechanical polishing, the grain size exhibits a gradient structure from the surface to the core, resulting in a Cu / Al multilayer composite plate with a dual heterogeneous structure combining heterogeneous layered and gradient structures. During tensile testing, the synergistic effect between the heterogeneous layered and gradient grain structures, along with the combined effect of multiple deformation mechanisms, improves the mechanical properties of the copper alloy.

Claims

1. A method for preparing a copper alloy with a dual heterostructure, characterized in that: The Cu / Al multilayer composite plate, which is cumulatively rolled, is annealed and then subjected to surface nano-sizing treatment. The specific preparation steps are as follows: (1) First, the pure aluminum plate and the pure copper plate are homogenized and annealed, and the oxide film and other impurities on the surface of the original plate are removed with acetone and an angle grinder. (2) Stack the pure copper plate and pure aluminum plate processed in step (1) together and rivet the two plates together; (3) The riveted copper and aluminum plates are rolled in a total of 8 passes to obtain Cu / Al multilayer composite plates. (4) Anneal the rolled Cu / Al multilayer composite plate at 350℃ for 10 min; (5) The surface of the Cu / Al multilayer composite plate after annealing is polished and the surface of the Cu / Al multilayer composite plate is nano-sized at room temperature to finally obtain a Cu / Al multilayer composite plate with dual heterostructure. The surface nano-sizing treatment described in step (5) is carried out in a high-energy ball mill with a test frequency of 50 Hz, 208 steel balls with a diameter of 8 mm, and a treatment time of 2 min.

2. The method for preparing the copper alloy with a dual heterostructure according to claim 1, characterized in that: In step (1), the annealing temperature of the pure aluminum plate is 370℃, the time is 2h, and it is furnace cooled; the annealing temperature of the pure copper plate is 500℃, the time is 2h, and it is furnace cooled.

3. The method for preparing a copper alloy with a dual heterostructure according to claim 1, characterized in that: In step (3), no preheating or lubrication is performed during the rolling process, and air cooling is used after rolling. The reduction rate is 50% each time.