Achieving Excellent Properties of Cu-Ni-Si Copper Alloy by Cold Rolling and Electropulsing Aging

Cold-rolled Cu-Ni-Si copper alloys were aged by electropulsing directly without the help of a furnace, and excellent strength and electrical conductivity were achieved. The strength and electrical conductivity reach 815 MPa and 38.9% IACS respectively for the sample aged by electropulsing with the frequency of 200 Hz for 10 min. The maximum electrical conductivity of samples, aged by electropulsing with the frequency of 400 Hz for 10 min, reaches 41.6% IACS. The conductivity of the sample aged at 200-400 Hz for 1 min is more than that of the sample aged by a furnace at 450 degrees C for 10 min. High-density delta-Ni2Si precipitates with size of 1-5 nm are found for the samples aged by electropulsing. Compared to the traditional aging treatment, electropulsing facilitates the diffusion of Ni and Si atoms to accelerate precipitation hardening. Additionally, cold rolling is also beneficial to the nucleation of precipitation and further improves the properties of Cu-Ni-Si alloy. Because electropulsing facilitates recrystallization at 300-500 Hz, this leads to decreased strength of copper alloy.