Abstract
Cu-Ni-Si alloys become the popular precipitation-hardening copper alloys recently. They are widely used for electrical applications such as electrical connectors, electrical springs and lead frames because of their high strength and high electrical conductivity. In order to substitute toxic Cu-Be alloys, many studies have suggested that the addition of other alloy elements and improvement of thermomechanical process can increase strength and electrical conductivity of Cu-Ni-Si alloys. The present report investigates the effect of Co replacing part of Ni atoms. We designed three kinds of Cu-Ni(-Co)-Si with different Co/Ni ratios: Cu-8Ni-4Si, Cu-6Ni-2Co-4Si, and Cu-4Ni-4Co-4Si. The samples after arc melting, solution heat treatment, cold rolling and aging process were conducted microstructure analysis and then examined the hardness, tensile strength and electrical conductivity. The experimental results show that the electrical conductivity increases with the increasing amount of Co addition. As for the hardness and tensile strength, listed from highest to lowest are Cu-6Ni-2Co-4Si、Cu-8Ni-4Si、Cu-4Ni-4Co-4Si.