LAUSR

Abstract The properties of Cu-0.2 wt%Zr-0.15 wt%Y alloy aged at 400 °C, 450 °C, 500 °C, 550 °C for 0 h, 0.25 h, 0.5 h, 1 h, 2 h, 4 h and 6 h after 0%, 20%, 40%, 60% cold rolling were investigated systematically by the transmission electron microscopy (TEM) and selected area electron diffraction (SAED) in this study. The hardness and electrical conductivity were measured under different conditions. The optimum ageing process for the alloy was determined. After solution treated at 900 °C for 1 h, the studied alloy with 60% cold rolling can obtain the best properties after aging treatment at 450 °C for 1 h. It means the conductivity can reach to 90.6 %IACS and the hardness reach to 145.0 HV. The ageing hardening behavior was also analyzed according to the transmission microstructures. A large amount of Cu10Zr7 precipitates were identified by TEM analysis in the copper matrix. The phase transformation kinetics equations for Cu-0.2 wt%Zr-0.15 wt%Y alloy was established under different aging temperature after 60% cold rolling. The kinetics curves of aging precipitation and isothermal transformation were obtained. In addition, the small addition of Y can promote the precipitation of the second phase.