Challenges in joining aluminium with copper for applications in electro mobility

The effective joining of aluminium with copper is one of the central technical goals involved in electro mobility. However, the joining of both metals by conventional fusion welding is challenging because of poor weldability arising from different chemical, mechanical and thermal properties of the materials and especially from the massive formation of hard and brittle intermetallic compounds (IMC) weld interface. In order to accomplish the difficult task of joining aluminium and copper several new joining technologies and strategies such as Laser Beam Welding (LBW) using highly dynamic beam deflection, Friction Stir Welding (FSW), Laser Induction Roll Plating (LIRP) and Electromagnetic Pulse Welding (EMPW) are under development at the Fraunhofer IWS. The current work describes the different technological approaches to the dissimilar joining of aluminium and copper. Thereby, the different joining technologies are compared with respect to weld quality. Special consideration is given to the study of interface morphology and microstructure of the welding zone. It will be shown that, depending on the joining method chosen the kind and extension of intermetallic phase formation differs considerably. Conclusions are drawn with respect to the applicability of the different joining methods.