The Comparison of Microstructure and Mechanical Properties of Diffusion Joints of 5754, 6061, and 7039 Aluminum Alloys to AZ31 Magnesium Alloy

In this study, microstructure and mechanical properties of diffusion joints between 5754, 6061 and 7039 aluminum alloys and AZ31 magnesium alloy were investigated. Diffusion joints were done between the alloys at 440 °C, for duration of 60minutes, at 29 MPa pressure and under 1×10-4 torr vacuum. The interface of joints was studied using optical (OM) and scanning electron microscopy (SEM) equipped with EDS analysis and the line scan. According to the results of EDS analysis, the presence of intermetallic compounds including Al12Mg17, Al3Mg2 and their mixture was observed at the diffusion zone. Also, according to the results of the line scan, the hardness value of aluminum alloys has a considerable effect on diffusion of the magnesium atoms toward aluminum alloy and the greatest diffusion of magnesium was observed when 6061 aluminum alloy was used. More diffusion resulted in a stronger bond between atoms of magnesium and aluminum, and maximum strength of approximately 42 MPa was obtained when 6061 aluminum alloy was used.