After solution aging treatment, fine black precipitates are densely distributed at the grain boundaries of chromium zirconium copper, and many small black precipitates are also distributed in the grain, with a size of about a few microns. As the temperature decreases, the curve approaches the copper side, and its solubility is only 0.03% at 400 °C. At this time, copper zirconium compound particles are precipitated in the solid solution. Therefore, chromium with a body-centered cubic structure, chromium with a close-packed hexagonal structure, and copper with a face-centered cubic structure are almost immiscible at room temperature, but copper and chromium cannot form compounds, while copper and zirconium can form a variety of compound phases. Chromium and zirconium can also form various compound phases. After heat treatment, the matrix of chromium zirconium copper is copper, and the precipitation phase is the intermetallic compound of Cr phase and chromium.
The tensile strength, yield strength and hardness of the chromium-zirconium-copper after heat treatment are increased, and the elongation after fracture is decreased. The chromium-zirconium-copper forms a supersaturated solid solution during solid solution, and the second phase and copper compounds are removed from the solid solution during the aging process. Precipitation, new phase dispersion strengthening. The second phase is dispersed and distributed in the matrix to form a coherent relationship with the matrix. There is a large mismatch at the coherent interface, which causes lattice distortion, which increases the elastic strain energy of the phase interface and improves the strength, hardness and elasticity of the alloy. . The electrical conductivity of chromium zirconium copper after heat treatment is higher than that before heat treatment. According to the theory of solid solution complex phase conductivity, the electrical conductivity of the aged metal is mainly controlled by the solid solubility of the solid solution matrix. At room temperature, the solubility of alloy elements in copper is very small. During the aging process, almost all alloy elements are continuously precipitated from the Cu matrix, and the content of solute elements in the solid solution gradually decreases until the solid solution tends to pure copper matrix, thereby improving the electrical conductivity.
Post time: Jul-06-2022