Microstructure characteristics and mechanical properties of the Cu/Al dissimilar joints by electric current assisted ultrasonic welding

Dissimilar joints of copper and aluminium alloy were generated by electric current assisted ultrasonic welding (EUSW). The microstructure characteristics and mechanical properties of Cu/Al EUSW joints were systematically investigated. The electric current promoted the plastic flow at the welding interface. The intermetallic thickness increased with electric current. The microstructure characteristics of Cu/Al joints welded by EUSW were compared with those of the Cu/Al joints welded by ultrasonic welding (USW). A thinner intermetallic compound layer could be obtained at the more fully material mixing during EUSW. The Cu/Al joints welded by EUSW displayed ultimate tensile strength 12% and fracture energy 21% greater than those of the Cu/Al joints welded by USW. The reasons for the improvement in mechanical properties of the Cu/Al EUSW joints have been discussed.