Effect of high contents of nickel and silicon on the microstructure and properties of Cu-Ni-Si alloys

Cu-Ni-Si alloys have been widely used in electronics and electrical industries.The preparation method of alloy was not limited to smelting, powder metallurgy method has also attracted the attention of many researchers. In this study, Cu-Ni-Si alloys were prepared using hot-pressed sintering and elemental copper powders, in which nickel and silicon powders were used as raw materials. The results show that, when the Cu-Ni-Si alloys were prepared using hot-pressed sintering, there were no Ni-Si intermetallic compounds except the delta-Ni2Si phase in the microstructure of alloys. After the ageing treatment, when the mass ratios of Ni/Si were 2:1 and 3:1, the precipitation of delta-Ni2Si phase was significantly less. However, when the mass ratios of Ni/Si were 4:1 and 5:1, the precipitation of delta-Ni2Si phase particles increased significantly. The results from electrical conductivity and Vickers hardness show that, after the ageing treatment, both the electrical conductivity and Vickers hardness of the alloys greatly improved.