Effect of Zr additions on the microstructure, and the mechanical and electrical properties of Cu–7 wt.%Ag alloys

Adding up to 0.05 wt.%Zr to Cu–7 wt.%Ag alloys suppresses the discontinuous precipitation mode in these alloys. As a consequence, the continuous precipitation mode, which is also commonly observed in these alloys, is enhanced. The addition of Zr in the mentioned range guarantees a minimum of secondary phases that contain Zr. The subjection of Cu–7 wt.%Ag–0.05 wt.%Zr alloys to a certain deformation strain followed by an intermediate heat treatment gives rise to a logarithmic drawing strain of up to ϕ=5.82 in these alloys. In this cold worked condition, an ultimate tensile strength of 1.4 GPa and a strain to failure of 1.6% are observed. Furthermore, an electrical conductivity of 60%IACS (IACS, International Annealed Copper Standard, i.e. the conductivity of copper) is measured. The influence of the Zr content, the thermal treatments, and the deformation process on the microstructure and thereby on the mechanical and electrical properties is discussed.