A novel Cu-Sn-Zr alloy with core-shell structure

Abstract

In this study, a novel Cu-0.3Sn-0.2Zr (wt.%) alloy was designed to investigate the influence of Zr addition on the microstructure and properties of the Cu-0.3Sn alloys. We have discovered that the addition of Zr could not only greatly refine the grain structures of the Cu-0.3Sn alloy and contribute to forming a large number of nanoscale Zr-rich particles, but also leads to the formation of core-shell structure with a large amount of Sn atoms segregated at the surface of the microscale and nanoscale Zr-rich particles. As a result, all of the tensile strength, electrical conductivity and softening temperature of the Cu-0.3Sn-0.2Zr alloy were improved when compared with the Cu-0.3Sn alloy. After cold drawing at an accumulated strain of 6.8 combined with a two-step aging treatment, a good combination of an ultimate tensile strength of ∼724 MPa, an electrical conductivity of ∼76.8% IACS and a softening temperature of ∼425 °C were achieved in the Cu-0.3Sn-0.2Zr alloy, which was ∼147 MPa, ∼0.7 % IACS and ∼90 °C higher than that of the Cu-0.3Sn alloy after cold drawing at the same accumulated strain of 6.8, respectively. Our research elucidates that the Cu-Sn-Zr alloys represent a category of potential copper alloys with high strength, high conductivity and excellent softening resistance performance.