Interfacial Microstructure and Hardness of Magnetic Pulse Welded Copper/Nickel Lap Joint

Abstract

Copper/nickel joint was fabricated using magnetic pulse welding and the interfacial microstructure was examined. Hardness change close to the welding interface was investigated by using a nanoindentation tester. Characteristic wavy morphology was formed at the welding interface. TEM observations and STEM-EDX analyses revealed that approximately 100 nm-diameter-fine grains of Cu-Ni solid solution were formed at both of copper and nickel regions in the vicinity of the welding interface. Remarkable hardness increase was detected at the vicinity of the welding interface in the nickel side, whereas hardness was constant in the copper side. The hardness increase is considered to be due to the combined effect of solid-solution strengthening and grain refinement strengthening.