Microstructure and properties evolution of a Cu–Ni–P alloy with high strength and high conductivity during thermomechanical treatment

Copper alloys with high strength and electrical conductivity are a key focus for next-generation electronic materials. In this study, a precipitation-strengthened Cu-0.96Ni-0.22P alloy with tensile strength, yield strength, and electrical conductivity values of 630 MPa, 614 MPa, and 64 % IACS, respectively, were designed via thermomechanical treatment. The nanoprecipitates remain in the form of the G.P zone during 450 °C aging from 30 to 120 min. Theoretical calculation results showed that the precipitation of coherent G.P zones contributes to a major strengthening to the Cu–Ni–P alloy. Coarsening of precipitates and recrystallization were the primary reasons for softening during the over-aged stage. The uniform growth of Ni2P phases was the main precipitation process during stable transformation, and the simultaneous precipitation of the Ni12P5 phase and a cube-like Ni3P phase was observed with a higher coarsening rate.