Microstructure and properties of the Cu–Co–Si–Ni–Cr–Zr alloy with high strength, high electrical conductivity and good softening resistance performance

Enhancing the strength, electrical conductivity and resistance to high-temperature softening is a crucial approach for facilitating the application of high-performance copper alloy in domains such as integrated circuit lead frames. Herein, a Cu–Co–Si–Ni–Cr–Zr alloy was designed, and the microstructure, mechanical and electrical properties of the alloy after different thermomechanical treatments were investigated in detail. The alloy demonstrated excellent comprehensive properties, with a hardness of 226 HV, a tensile strength of 720 MPa, an electrical conductivity of 67.5% IACS and a softening temperature of 575 °C after multi-stage thermomechanical treatment. The addition of Ni and Si elements in Cu–Co–Si alloy promoted the diffuse precipitation of Co, leading to the formation of Co 2 Si and Ni 2 Si precipitation phases. Besides, the small amount of Cr element further promoted the precipitation of Si to form precipitated phases such as Cr 5 Si 3 . The different precipitates effectively impede dislocation motion and grain boundary migration, contributing to good strength and resistance to high-temperature softening of the Cu–Co–Si–Ni–Cr–Zr alloy.