Solid-state welding of aluminum to copper—case studies

This paper describes procedures for the joining of aluminum with copper via solid-state welding. Welding of dissimilar materials in order to reach a high strength and durable joints is a reasonable and outstanding challenge for industrial and especially for automotive applications. Nowadays, wiring and electrical systems, as for example batteries, turn out to be main drivers for new developments in the field of dissimilar joining technologies. Joining of aluminum to copper through a melting process leads to brittle intermetallic compounds, which cause failure of the joint already during cool down. Solid-state welding technologies allow the welding below melting temperature, so that phenomena at the interface, which lead to the formation of intermetallics under different conditions, are of interest to the resulting joint properties. Not only mechanical properties, but electrical resistivity and heat conduction are strongly dependent on those effects. Diffusion welding is performed as a model welding procedure, while friction stir welding and hybrid friction diffusion bonding are investigated as technological welding processes in this paper.