Microstructural control of the interface layer for strength enhancement of dissimilar Al/Cu joints via ni addition during tig arc brazing

Abstract

Dissimilar metal joining between Al and Cu is effective for reducing the weight and cost of electrical components. In this study, dissimilar lap joining of pure Al to pure Cu with an Al-Ni filler material was conducted using tungsten inert gas (TIG) arc brazing, and the effect of Ni on the joint strength associated with the microstructure of the intermetallic compound (IMC) layer at the dissimilar interface was examined. The addition of Ni effectively increased the interfacial strength of the joints. Regardless of the addition of Ni, the joints fractured in the thick Al2Cu layer formed at the Al/Cu interface. However, the Ni addition reduced the thickness of the IMC layer and led to the formation of Al7Cu4Ni particles in the weakest Al2Cu layer. Both the thickness reduction and rein-forcing Al7Cu4Ni particle formation are thought to contribute to the increase in joint strength of the Al/Cu dissimilar interface.