Effect of joining temperature on microstructure and properties of Mg/Al diffusion bonded joints

Basing on vacuum diffusion bonding technique, Mg1 and Al1060 were welded under different welding temperatures. Inspection equipment such as scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometer, and tensile machine were applied to observe and investigate the microstructure, phase composition and mechanical property of Mg/Al diffusion welding joints. The results indicate that Mg1/Al1060 diffusion layers generate in the joints, and the thickness progressively increases with ascending welding temperature. From Al to Mg side, diffusion layers are comprised of Mg₂Al₃, Mg₁₇Al₁₂, and Mg₁₇Al₁₂ + Mg based solid solutions sequentially. The shear resistance of the joints increases and then decreases with the increasing welding temperature. At 440 ℃, the maximal shear strength of 13 MPa can be obtained, and fracture results from Mg₂Al₃ phase near Al side.