Strontium modification and formation of cubic primary Mg2Si crystals in Mg2Si/Al composite

The effect of Sr content on microstructure of Mg2Si/Al composite was investigated by XRD, SEM and extracted technology. The results showed that, with the increase of Sr content, primary Mg2Si morphology changes from dendritic to polygonal and then to quadrangle with a size of ∼40 μm. The extracted results indicated that, the unmodified Mg2Si is an assembly of octahedral with a common orientation. However, after 0.1–0.15 wt.% Sr addition, the particle morphology is cubic. Furthermore, there exist some twin crystals and fine crystals. The formation mechanism of cubic Mg2Si particle was discussed.