Friction Stir Welding (FSW) is a suitable technology to join dissimilar metals since the solidus temperature is not exceeded during the process in contrast to fusion welding processes. To weld dissimilar joints in a high quality, a minimum of deleterious lower conducting or brittle intermetallic phases is required. However, a substance-to-substance bond by an interface layer is crucial to join dissimilar metals. A comprehensive description of the effective joining mechanisms is still subject of an ongoing research. Therefore, the formation of the intermetallic phases in the interface layer has to be analyzed in detail.
The formation of nano-scaled intermetallic layers at the bonding interface was analyzed in this study. For this purpose, dissimilar lap joints of aluminium with copper and aluminium with titanium have been investigated. The length of the pin of the welding tool was set to only stir in the aluminium. The results showed that the thickness of the intermetallic layer highly depends on the process temperature, which varies with different process parameters. Understanding the relevant process parameters for the formation of the interlayer is necessary to control the joint quality.