Formation of Intermetallic Compounds at the Interface of the Friction Stir Weld and Diffusion Bond of Mg-AZ31/Al-5083 Joint

Abstract

Dissimilar Friction stir and Diffusion bond welds of Al alloy 5083 and Mg alloy AZ31 were produced. The maximum temperature at the advancing side of friction stir weld rose to a maximum of 435°C. This temperature was selected as the bonding temperature, for diffusion bonding of these two alloys. The diffusion bonding time was 60 min. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to investigate the compositional changes across the joint region. Dissimilar FS weld, produced layers of new phases of Al12Mg17 and Al3Mg2 intermetallics. DB weld, produced a melted-andsolidified eutectic structure consists a hypo-eutectic structure in the middle of the joint and a two layer structure between the eutectic and the Al base. The shear strength of joint corresponding to DB welded specimen was 43.2 MPa. The tensile strength of joint corresponding to FS welded specimen was 51.3 MPa. The present study suggests that constitutional liquation resulted in the intermetallic compound formation in the weld center.