Ultrasonic welding of copper alloys: a review

Ultrasonic welding, an advanced green manufacturing technology with remarkable energy-saving characteristics, demonstrates significant advantages in welding dissimilar light alloys. This paper provides a comprehensive overview of global research advancements in ultrasonic welding technology for copper alloys over the past 15 years, systematically summarizing for their homogeneous and heterogeneous combinations, addressing key factors such as microstructure, microhardness, interface temperature, joint strength and welding mechanisms. Maximum strength of Cu/Cu joints approaches the base material; Cu/Al, Cu/Ni and Cu/Steel heterogeneous joints approach the weaker base metal, while Cu/Mg joints is lower than that of the base material. Cu/Al and Cu/Ni welding is primarily attributed to the combined effects of plastic deformation and interfacial metallurgical reactions, Cu/Mg and Cu/Steel welding mainly relies on interfacial metallurgical reactions. Strategies like optimising parameters, modifying lap joint configurations and introducing interlayers enhance strength. This work offers a valuable reference for researchers worldwide engaged in ultrasonic welding studies.