Effect of brazing temperature and holding time on microstructure and strength of brazed joints between dissimilar materials Mg/Al

In the present work, low temperature brazing of Mg/Al dissimilar metal with Sn-30Zn solder is successfully realized.Microstructure of the brazed joints is analyzed by scanning electron microscopy(SEM) and electronic probe micro-analyzer(EPMA).Microhardness and shear strengh of the joints are also investigated by Vickers hardness tester and universal material machine, respectively.The result shows that excellent microstructure and mechanical properties will be obtianed while the brazing temperature is 330℃ and holding time is 5 s.The microstructure of joint consists of a multilayer sandwich structure which comprise transition zone of Mg₂Sn near the Mg base metal, transition zone of Al-Sn-Zn solid solution near the Al base metal, and the central zone between them.The Mg₂Sn and Al-Sn-Zn solid solution phases are dispersed in Sn-Zn hypereutectic structure at this zone.With these brazing prameters, the average shear strength of the brazed joints is 60.47 MPa.