Abnormal improvement on electrical conductivity of Cu-Ni-Si alloys resulting from semi-solid isothermal treatment

The effect of semi-solid isothermal treatments on electrical conductivities of Cu-Ni-Si alloys with the addition of 10 wt.%Ni + Si was studied in conjunction with different solid-state solution treatments. The microstructure and phase composition of as-treated samples were investigated. The results showed that after semi-solid isothermal treatments at 1000°C, both the complete decomposition of δ-Ni ₂Si phases in Cu-rich solutions and the remelting of eutectic phases at the grain boundaries had occurred. As a result, an abnormal improvement on the electrical conductivities of Cu-Ni-Si alloys could be obtained due to lower scatter effect of Ni and Si atoms on electron movement, resulting from more Ni and Si atoms in Cu-rich solutions entered into the eutectic melts at the grain boundaries by solid-state diffusion.