CN101392359A - A kind of preparation method of high-strength, high-conductivity pure copper material - Google Patents

Abstract

The invention provides a method for preparing a high-strength, high-conductivity pure copper material. The copper material is subjected to recrystallization annealing at a temperature of 300-700°C for 0.5-5 hours; when the deformation temperature is lower than -100°C, the strain rate is 10 Forging copper material under the condition of ^-5 /s～10 ² /s to make it plastically deformed at low temperature, using the drawing process to continue to plastically deform pure copper at low temperature, and prepare pure copper with nano-twin structure The material has high strength and good electrical conductivity, which overcomes the disadvantages of reducing the electrical conductivity of the copper material while increasing the strength of the copper material in the prior art. The strength of the copper material obtained by the invention is higher than 450 MPa, and the electrical conductivity is not lower than 90% IACS.

Description

A kind of preparation method of high-strength, high-conductivity pure copper material

technical field

The invention relates to a preparation method of a pure copper material, in particular to a preparation method of a pure copper body material having both high strength and high conductivity, and belongs to the technical field of metal material manufacture.

Background technique

According to the Hall-Petch relationship, the yield stress of polycrystalline materials has the following relationship with the grain size, namely: σ _y = σ ₀ +Kd ^-1/2 , where σ _y is the 0.2% yield stress, and σ ₀ is the moving single dislocation The force required to overcome lattice friction, K is a constant, d is the average grain size, that is, as the grain size of the material decreases, the proportion of grain boundaries increases greatly, and the lattice friction that dislocations need to overcome As the force increases, the yield strength of the material increases. The use of large plastic deformation (SPD) can refine the grain size of the material to the ultrafine grain size (100-1000nm), thereby improving the strength of the material. However, due to the rapid increase of the proportion of grain boundaries, various physical properties of the material change. Due to the scattering effect of grain boundaries on electrons, the increase of grain boundaries greatly reduces the conductivity of the material. Generally, the conductivity of pure copper after large plastic deformation can only reach 10% to 40% IACS. Is it possible to make materials with high strength while maintaining high conductivity? As a special grain boundary, the twin boundary can not only hinder the movement of dislocations like ordinary grain boundaries, but also have lower energy than ordinary grain boundaries. If a large number of twins can be introduced into the material, then It can not only improve the strength of the material, but also not significantly reduce the conductivity of the material.

Metals with a face-centered cubic structure (such as pure copper) will not produce deformation twins under ordinary deformation conditions (room temperature, low speed). However, molecular dynamics simulation experiments and related studies have shown that under the conditions of low temperature (liquid nitrogen temperature) and high deformation rate, deformation twins can also be produced in metals with a face-centered cubic structure. The innovation of the present invention is that through the control of the deformation process conditions and deformation temperature, a large number of deformation twins are introduced into the pure copper with a face-centered cubic structure, and the strength of the material is improved through the hindering effect of the twin boundaries on dislocation movement, and at the same time , since the twin boundary is a low-energy interface, it will not significantly reduce the conductivity of the material.

4. Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a pure copper body material with high strength and high conductivity at the same time. The method is simple in process and can obtain a pure copper body material with a nano-twin structure .

The method of the invention is realized through the cooperation of forging and drawing combined pressure processing technology. First, the free forging process is used to make the pure copper plastically deform at low temperature. After reaching the required strain, the drawing process is used to continue to make the pure copper plastically deform at low temperature. By controlling the deformation rate, deformation temperature and strain, a nano-twin structure is introduced into the pure copper during the deformation process to obtain a pure copper material with a nano-twin structure, and the pure copper material has high strength and electrical conductivity performance.

The present invention is specifically accomplished through the following technical solutions: a method for preparing a high-strength, high-conductivity pure copper material, which is characterized in that the process steps are as follows:

A. Anneal the copper material at a temperature of 300-700°C for 0.5-5 hours to recrystallize it;

B. Place the above-mentioned recrystallized copper material in liquid nitrogen and soak until the temperature of the copper material itself reaches the liquid nitrogen temperature, then take it out;

C. Under the condition that the deformation temperature is lower than -100°C and the strain rate is 10 ^-4 /s ~ 10 ² /s, the copper material is forged to plastically deform until the total true strain reaches -1 ~ -4;

D. Cool the copper material in liquid nitrogen, and draw the copper material under the condition that the deformation temperature is lower than -100°C and the strain rate is 10 ^-5 /s～10 ² /s, so that it can be plastically deformed to the total The true strain reaches -3~-8, that is, a pure copper material with a nano-twin structure.

The annealing treatment is a conventional annealing process in the prior art.

The forging is a conventional forging process in the prior art.

The drawing is a conventional drawing process in the prior art.

The pure copper body material with nano-twin structure prepared by the process of the invention has a strength higher than 450 MPa and an electric conductivity not lower than 90% IACS.

The object of the present invention is to prepare a pure copper material with a nano-twin structure through the control of the deformation process parameters, so that the prepared pure copper body material has a high strength, and at the same time, the electrical conductivity is not significantly reduced, which overcomes the traditional process. While improving the strength of the pure copper body material through work hardening, its electrical conductivity is significantly reduced. At the same time, the copper material prepared by this method has the characteristics of large volume, which provides convenience for the measurement of the relevant mechanical properties and physical properties of the material, and at the same time lays the foundation for the practical application of the material.

6. Specific implementation

Example 1

A. Anneal a pure copper rod with a diameter of 10mm at a temperature of 300°C for 5 hours to recrystallize it;

B. Place the above-mentioned recrystallized copper material in liquid nitrogen and soak until the temperature of the copper material itself reaches the liquid nitrogen temperature, then take it out;

C. Under the condition that the deformation temperature is lower than -100°C and the strain rate is 10 ^-4 /s ~ 10 ² /s, the copper material is forged with the existing technology, so that it undergoes plastic deformation until the total true strain reaches -1;

D. Cool the copper material in liquid nitrogen. Under the condition that the temperature is not higher than -100°C and the strain rate is 10 ^-5 /s ~ 10 ² /s, the copper material is drawn with the existing technology to make it happen Plastic deformation until the total true strain reaches -3, that is, a pure copper material with a nano-twin structure.

Example 2

A. Anneal a pure copper rod with a diameter of 50mm at 700°C for 2 hours to recrystallize it;

B. Place the above-mentioned recrystallized copper material in liquid nitrogen and soak until the temperature of the copper material itself reaches the liquid nitrogen temperature, then take it out;

C. Under the condition that the temperature is not higher than -100°C and the strain rate is 10 ^-4 /s ~ 10 ² /s, forge copper with the existing technology to make it plastically deform until the total true strain reaches -4;

D. Cool the copper material in liquid nitrogen. Under the condition that the temperature is not higher than -100°C and the strain rate is 10 ^-5 /s ~ 10 ² /s, the copper material is drawn with the existing technology to make it happen Plastic deformation until the total true strain reaches -8, that is, a pure copper material with a nano-twin structure.

Example 3

A. Anneal a pure copper rod with a diameter of 30mm at a temperature of 500°C for 1 hour to recrystallize it;

B. Place the above-mentioned recrystallized copper material in liquid nitrogen and soak until the temperature of the copper material itself reaches the liquid nitrogen temperature, then take it out;

C. Under the condition that the temperature is not higher than -100°C and the strain rate is 10 ^-4 /s ~ 10 ² /s, forge copper with the existing technology to make it plastically deform until the total true strain reaches -2;

D. Cool the copper material in liquid nitrogen. Under the condition that the temperature is not higher than -100°C and the strain rate is 10 ^-5 /s ~ 10 ² /s, the copper material is drawn with the existing technology to make it happen Plastic deformation until the total true strain reaches -5, that is, a pure copper material with a nano-twin structure.

Example 4

A. Anneal a pure copper rod with a diameter of 20mm at 400°C for 2 hours to recrystallize it;

B. Place the above-mentioned recrystallized copper material in liquid nitrogen and soak until the temperature of the copper material itself reaches the liquid nitrogen temperature, then take it out;

C. Under the condition that the temperature is not higher than -100°C and the strain rate is 10 ^-4 /s ~ 10 ² /s, forge copper with the existing technology to make it plastically deform until the total true strain reaches -3;

D. Cool the copper material in liquid nitrogen. Under the condition that the temperature is not higher than -100°C and the strain rate is 10 ^-5 /s ~ 10 ² /s, the copper material is drawn with the existing technology to make it happen Plastic deformation until the total true strain reaches -6, that is, a pure copper material with a nano-twin structure.

Claims (4)

1, a kind of preparation method of high-strength, high-conductivity pure copper material is characterized in that through following processing steps: A. Anneal the copper material at a temperature of 300-700°C for 0.5-5 hours to recrystallize it; B. Place the above-mentioned recrystallized copper material in liquid nitrogen and soak until the temperature of the copper material itself reaches the liquid nitrogen temperature, then take it out; C. Under the condition that the deformation temperature is lower than -100°C and the strain rate is 10 ^-4 /s ~ 10 ² /s, the copper material is forged to plastically deform until the total true strain reaches -1 ~ -4; D. Cool the copper material in liquid nitrogen, and draw the copper material under the condition that the deformation temperature is lower than -100°C and the strain rate is 10 ^-5 /s～10 ² /s, so that it can be plastically deformed to the total The true strain reaches -3~-8, that is, a pure copper material with a nano-twin structure. 2. The method for preparing high-strength, high-conductivity pure copper material according to claim 1, characterized in that the forging is a conventional forging process in the prior art. 3. The method for preparing high-strength, high-conductivity pure copper material according to claim 1, characterized in that the drawing is a conventional drawing process in the prior art. 4. The method for preparing high-strength, high-conductivity pure copper material according to claim 1, characterized in that the annealing treatment is a conventional annealing process in the prior art.