Optimizing mechanical and electrical properties of Cu–3Zr alloy by thermomechanical processing

Cu–3Zr alloy was prepared by powder metallurgy and two-stage thermomechanical process, and the microstructure evolution and properties were investigated. The results show that the microstructure of as-sintered Cu–3Zr alloy is consisted of the coarse Cu–Zr intermetallic compounds and equiaxed Cu grains. After extrusion, the second phase is smaller in cross section, while deformation texture of the Cu matrix can be seen from longitudinal section. After further drawing, the Cu grains are elongated and the Cu–Zr intermetallic phase is broken into fine particles. The yield strength (YS), ultimate tensile strength (UTS) and electrical conductivity are 593 MPa, 684 MPa, and 74%IACS, which are respectively increased by 38%, 34% and 21% as compared to the as-sintered Cu–3Zr alloy. Phase analysis and microstructural characterization demonstrate that the Cu5Zr, Cu8Zr3, and Cu10Zr7 precipitates are uniformly distributed in the Cu matrix. Cu5Zr/Cu and Cu8Zr3/Cu are combined in the form of coherent relation. Cu10Zr7/Cu are combined in the form of semi-coherent relation. The enhanced mechanical properties can be attributed to the multiple synergistical strengthening effect. The elongated Cu grains and fine Cu–Zr precipitation phases block the movement of dislocation, resulting in the remarkable enhancement of strength. Moreover, the elongated Cu grains can provide fast channel for the electron transport, giving rise to simultaneous increase of the electrical conductivity.