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.