Microstructure and Properties of Cu-3.2Ni-0.75Si-0.3Zn Alloy for Lead Frame

The effect of aging temperature and aging time on properties of Cu-3.2Ni-0.75Si-0.3Zn alloy were studied. The alloys were isochronally or isothermally aged after solution treatment. The cold rolling prior to the aging treatment was used to increase the precipitation rate .The microstructure of the alloy was studied by means of transmission electron microscope (TEM). The results show that the fine and dispersed precipitates are fully coherent with the Cu matrix and make the alloy possesses higher hardness and conductivity after the alloy was solution at 1173K and then aged at different time. The precipitates responsible for the age-hardening effect was Ni2Si.The transformation kinetics were studied by analyzing the electrical resistance variation of the solution Cu-3.2Ni-0.75Si-0.3Zn alloy in the process of aging.