Electrical and mechanical properties of Cu−Cr−Zr alloy aged under imposed direct continuous current
(Department of Materials Engineering, Shanghai University, Shanghai 200072, China)
Abstract: The Cu−Cr−Zr alloys were aged at different temperatures for different time with different current densities. The results show that both the electrical conductivity and hardness are greatly improved after being aged with current at a proper temperature. The electrical conductivity increases approximately linearly with increasing current density while the hardness remains constant. The microstructure observation reveals that a much higher density of dislocations and nanosized Cr precipitates appear after the imposition of current, which contributes to the higher electrical conductivity and hardness. The mechanism is related with three factors: 1) Joule heating due to the current, 2) migration of mass electrons, 3) solute atoms, vacancies, and dislocations promoted by electron wind force.
Key words: Cu−Cr−Zr alloy; electrical conductivity; hardness; current ageing; precipitation