Friction stir-induced brazing of Al/Mg lap joints with and without Zn interlayer

The interfacial structure and mechanical properties of Al/Mg joints with and without Zn interlayer by friction stir-induced brazing bond have been investigated. The results revealed that the formation of brittle Al–Mg intermetallics could be effectively suppressed by the addition of Zn interlayer and using appropriate welding parameters, which were replaced by α(Mg)+Mg–Zn and Al–Mg–Zn intermetallic. When rotation speed was further increased, Al–Mg intermetallics were formed again at the interface. The shear strength of Al/Mg joints with Zn interlayer was improved by up to ～25% in comparison with those of the joints without Zn interlayer. A mixture of ductility and cleavage fracture occurred on fracture surfaces of Zn-added joints which was different from the cleavage fracture feature of the direct joints.