Effects of Zr and (Ni, Si) additions on properties and microstructure of Cu–Cr alloy

Abstract

The properties and microstructure of Cu–Cr alloy with Zr and (Ni, Si) additions were investigated. Improvements of peak-hardness and softening resistance are achieved with Zr and (Ni, Si) additions in the Cu–Cr alloy, while only a slight decrease in conductivity is brought out. Good balance of hardness and electrical conductivity, which reach to 177 HV and 82.2% IACS respectively, can be obtained in the Cu–Cr–Zr–Ni–Si alloy after 80% cold rolling and 450 °С aging for 360 min. The solutes-rich particles in cast microstructure and aged precipitates are refined and homogeneously distributed with the addition of alloying elements. Stacking fault energy of the Cu–Cr alloy decreases with the additions of Zr and (Ni, Si) elements, leading to easy and extensive occurrence of stacking faults and twins. Precipitate morphology of Cu–Cr alloy can be modified by the additions of alloying elements, which is associated with the interface energy of precipitates in the over-aged Cu–Cr–Zr and Cu–Cr–Zr–Ni–Si alloy.