Interfacial Microstructure Evaluation of Precisely Controlled Friction Stir Welding Joints of Al/Mg Dissimilar Alloys with Zn Interlayer

In this study, a penetration-controlled friction stir welding (FSW) technique was employed to lap weld dissimilar Al/Mg alloys, incorporating Zn interlayer. The joint’s microstructure, interfacial reaction, and phase composition were analyzed through optical microscopy, scanning electron X-ray diffraction. findings demonstrate the formation of hybrid joint comprising FSWed region diffusion bonding achieved by introducing pure interlayer at interface. Within region, zinc fully extruded, leading favorable interface bonding. contrast, exhibited an aluminum–zinc reaction layer, incompletely reacted zinc–magnesium layer. Notably, no Al-Mg intermetallic compounds (IMCs) observed in either or regions joint. This study further explored underlying mechanism behind formation.