Effects of solution heat treatment on microstructure and mechanical properties of Mg–3Al–1Si–0.3Mn–xSr alloy

The effects of solution heat treatment on the microstructure and mechanical properties of Mg–3Al–1Si–0.3Mn–xSr (x=0, 0.2, 0.4) alloy were investigated. After adding Sr, the coarse Chinese Mg₂Si phase had been greatly refined. Sr could play a role in the surface refinement and form a new binary or multiple phases with the matrix elements, however excessive Sr has no metamorphism. After solution treatment, magnesium alloy showed spheroidization and Mg₂Si phase experienced the process from passivation to fusion. The mechanical properties of the alloy had been significantly improved in T4-420 °C×10 h treatment process. It had the best mechanical properties of the three alloys. After aging treatment, the microstructure of the alloy had no obvious change and the mechanical properties had a slight increase. The tensile properties of the alloy were approximately proportional to the holding time