A bonded structure of aluminum and copper is formed by bonding a copper workpiece and an aluminum workpiece together along a joint via an arc welding process. The copper workpiece has a first coating, having a lower melting point than copper, applied to at least a portion of it. The first coating allows the copper workpiece to be wetted and brazed, while the aluminum workpiece is melted and fused along the joint. The arc welding process involves the cyclic alternating of a first stage, in which an electric current is supplied to a welding wire as it is moved toward the workpieces, and a second stage, in which the electric current is reduced and the welding wire is moved away from the workpieces, to generate and detach a plurality of molten droplets along the joint. Each molten droplet is formed from the welding wire in the first stage.