Preparation method of copper-germanium alloy with heterostructure

Abstract

The invention discloses a preparation method of a copper-germanium alloy with a heterostructure, and belongs to the technical field of material preparation. According to the method, a smelted and formed plate is subjected to a cold rolling process, then the rolled plate is subjected to short-time annealing treatment, and finally the copper-germanium alloy material of the heterostructure is obtained. According to the method, the copper-germanium plate is subjected to cold rolling treatment with the total deformation of 50% and 60% at the room temperature, and wide recrystallization behaviors are generated through parameter regulation and control in follow-up annealing, so that the grain size difference is formed. The prepared material has a large number of defects, due to the interaction of the defects, the work hardening rate of the material is increased, and therefore the plasticity is improved.

Description

Technical Field

[0001] The invention relates to a method for preparing a heterostructure copper-germanium alloy, belonging to the technical field of material preparation. Background Art

[0002] Copper-germanium alloys are widely used in modern engineering technology due to their good electrical conductivity, thermal conductivity, corrosion resistance, and easy cutting performance. They are commonly used in machinery manufacturing, information communication, aerospace, electrical, electronic, construction, chemical, energy and other fields. However, with the continuous development of science and technology, traditional copper-germanium alloy materials and processing methods have been unable to meet the higher performance requirements of the industry, which has largely hindered their further development and application in the corresponding fields.

[0003] Yield strength and plasticity are a pair of incompatible performance characteristics in copper-germanium alloys. For traditional coarse-grained materials, reducing the grain size can simultaneously increase strength. However, studies have found that if the grain size is reduced to the nanoscale, although the strength of the metal material can be greatly improved, the plasticity is very low, and even brittle, which limits its application in the field of structural materials. For nano-metal materials, local deformation occurs in the early stage of plastic deformation, necking occurs prematurely, and eventually fractures.

[0004] In view of such a problem, the present invention proposes a method of large plastic deformation rolling plus short time annealing to process two copper-germanium alloy samples with different stacking fault energies. Summary of the invention

[0005] In order to solve the problems existing in the existing copper-germanium alloy, the present invention provides a method for preparing a heterostructure copper-germanium alloy, and the specific steps are as follows:

[0006] (1) Copper and germanium are melted and formed to obtain copper-germanium plates.

[0007] (2) The copper-germanium plate obtained in step (1) is polished and then cold-rolled to obtain a copper-germanium plate.

[0008] (3) Annealing the copper-germanium plate obtained in step (2) at a temperature in the range of 350 to 500° C. for 20 min to obtain a heterostructure copper-germanium alloy.

[0009] Preferably, the atomic percentage of germanium in the copper-germanium plate obtained in step (1) is 5.7% to 9.0%, and the rest is copper, wherein the copper is oxygen-free pure copper with a purity of 99.95%; the purity of the germanium is greater than 99.9%.

[0010] Preferably, the total deformation amount of the cold rolling treatment in step (2) is 50% to 60%.

[0011] Beneficial effects of the present invention

[0012] (1) The copper-germanium alloy prepared by the present invention forms a double-peak structure of grains through rolling and short-time annealing, thereby obtaining a copper-germanium alloy with a heterogeneous structure, so that the strength and plasticity of the material are well matched. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The tensile curves of the copper-germanium plates prepared in Examples 1 and 2 of the present invention and the original annealed samples at room temperature are compared.

[0014] Figure 2 This is the metallographic phase diagram of the copper-germanium alloy crystal prepared in Example 1.

[0015] Figure 3 This is a hardness diagram from the surface to the core of the copper germanium prepared in Example 1, which is completely annealed and not annealed. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0017] The copper used in the embodiment is oxygen-free pure copper with a purity of 99.95%; the germanium used has a purity greater than 99.9%.

[0018] Example 1

[0019] A method for preparing a heterostructure copper-germanium alloy, the specific steps are as follows:

[0020] (1) Copper and germanium are smelted and formed to obtain a copper-germanium alloy plate with a thickness of 10 mm, wherein the atomic percentage of germanium in the copper-germanium alloy plate is 5.7%.

[0021] (2) The copper-germanium alloy plate obtained in step (1) is polished and then rolled at room temperature to obtain a copper-germanium alloy plate, wherein the total deformation of the rolling is 60%.

[0022] (3) Annealing the copper-germanium plate obtained in step (2) at a temperature of 400° C. for 20 min to obtain a heterostructure copper-germanium alloy.

[0023] Example 2

[0024] A method for preparing a heterostructure copper-germanium alloy, the specific steps are as follows:

[0025] (1) Copper and germanium are smelted and formed to obtain a copper-germanium alloy plate with a thickness of 10 mm, wherein the atomic percentage of germanium in the copper-germanium alloy plate is 5.7%.

[0026] (2) The copper-germanium alloy plate obtained in step (1) is polished and then rolled at room temperature to obtain a copper-germanium alloy plate, wherein the total deformation of the rolling is 60%.

[0027] (3) Annealing the copper-germanium plate obtained in step (2) at a temperature of 500° C. for 20 min to obtain a heterostructure copper-germanium alloy.

[0028] Comparative Example 1

[0029] A preparation method of an unannealed copper-germanium alloy, the specific steps are as follows:

[0030] (1) Copper and germanium are smelted and formed to obtain a copper-germanium alloy plate with a thickness of 10 mm, wherein the atomic percentage of germanium in the copper-germanium alloy plate is 5.7%.

[0031] (2) After grinding the copper-germanium alloy plate obtained in step (1), rolling is performed at room temperature to obtain a copper-germanium alloy plate, and the total deformation of the rolling is 60% for standby use, thereby obtaining an unannealed sample. The yield strength of the sample is 303 MPa, and the uniform elongation is 32%.

[0032] Comparative Example 2

[0033] A preparation method of Cu5.7Ge annealed copper-germanium alloy, the specific steps are as follows:

[0034] (1) Copper and germanium are smelted and formed to obtain a copper-germanium alloy plate with a thickness of 10 mm, wherein the atomic percentage of germanium in the copper-germanium alloy plate is 5.7%.

[0035] (2) The copper-germanium alloy plate obtained in step (1) is polished and then rolled at room temperature to obtain a copper-germanium alloy plate, wherein the total deformation of the rolling is 60%.

[0036] (3) The copper-germanium plate obtained in step (2) is vacuum annealed at 700° C. for 2 h to obtain an annealed copper-germanium alloy having a yield strength of 96 MPa and a uniform elongation of 68%.

[0037] In order to verify the mechanical properties of the treated copper-germanium alloy plate, the copper-germanium alloy plate prepared in Example 1 and Example 2 was subjected to electric spark wire cutting, and without affecting the metal structure, a dog-bone-shaped tensile specimen was cut under a tensile testing machine to obtain a tensile curve. The mechanical properties of the heterostructure copper-germanium alloy material obtained by rolling and short-time annealing in this embodiment are as follows:

[0038] The yield strength of the copper-germanium alloy prepared in Example 1 can reach 264MPa, which is 3 times that of the Cu5.7Ge annealed copper-germanium alloy prepared in Example 2 (shown by the "▲" curve in the figure), and the uniform elongation reaches 45%. The yield strength of the copper-germanium alloy obtained in Example 2 can reach 110MPa, which is 1.2 times that of the Cu5.7Ge annealed copper-germanium alloy prepared in Example 2 (shown by the "▲" curve in the figure), and the uniform elongation reaches 60%. Combining the comparison of the two, although the elongation of the sample of Example 2 annealed at 500°C is good, the strength is equivalent to that of the annealed state of Example 2, and the elongation is reduced. The strength of Example 1 at 400°C is 3 times higher than that of the annealed state of Example 2, and the elongation is maintained at a certain level, which is 13% higher than that of the unannealed sample in Example 1, and the strength is not much different. Then, excellent strong-plastic matching characteristics are achieved.

[0039] Figure 2 This is the metallographic diagram of the copper-germanium alloy material prepared in Example 1. From the metallographic diagram, it can be seen that the grains of the sample after rolling and short-time annealing are of different sizes, and the size span of the grains is obvious. It may be because the growth rate of recrystallized grains is faster at 400°C, and the difference in the growth rate of grains leads to significant differences in grain size. It is precisely because of this grain structure that its strength and plasticity are well matched.

[0040] Figure 3 The microhardness curves of the prepared copper-germanium heterostructure and the fully annealed one show that the hardness of the copper-germanium heterostructure prepared in Example 1 fluctuates greatly at different positions, indicating that the sample has formed an uneven structure. In contrast, the hardness value of the coarse-grained sample is 80Hv, and the hardness fluctuation of the sample is also smaller, which means that the coarse-grained sample has formed a more uniform structure. This is consistent with Figure 2 The metallographic diagram shows that the hardness of different positions varies greatly, which is due to the cross-distribution of large and small grains on the metallographic diagram. Figure 1 The large grains (soft area) provide plasticity for the material, while the small grains (hard area) provide strength for the material, satisfying the strong-plastic matching between the materials.

[0041] The present invention successfully prepares a heterostructure copper-germanium alloy, which has the characteristics of both a grain bimodal structure and a heterogeneous structure. The preparation of heterogeneous materials is to achieve excellent strength-plasticity matching characteristics, thereby alleviating the inverted relationship between strength and ductility of traditional metal materials to a certain extent. In the mechanical tensile test, the synergistic effect between the bimodal hard and soft areas, the surface structure and the core structure, and the combination of multiple deformation mechanisms jointly improve the mechanical properties of the copper-germanium alloy. Specifically, the yield strength is increased by 3 times while maintaining good plasticity.

Claims

1. A method for preparing a heterostructure copper-germanium alloy, characterized in that: The specific steps are as follows: (1) melting copper and germanium to obtain a copper-germanium plate; (2) grinding the copper-germanium plate obtained in step (1) and then cold-rolling it to obtain a copper-germanium plate; (3) Annealing the copper-germanium plate obtained in step (2) at a temperature in the range of 350 to 500° C. for 20 min to obtain a heterostructure copper-germanium alloy.

2. The method for preparing the heterostructure copper-germanium alloy according to claim 1, characterized in that: The atomic percentage of germanium in the copper-germanium plate obtained in step (1) is 5.7% to 9.0%, and the rest is copper, wherein the copper is oxygen-free pure copper with a purity of 99.95%; the purity of the germanium is greater than 99.9%.

3. The method for preparing the heterostructure copper-germanium alloy according to claim 1, characterized in that: The total deformation amount of the cold rolling treatment in step (2) is 50% to 60%.

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