Heterogeneous nucleation of Mg2Si on Sr11Sb10 nucleus in Mg–x(3.5, 5 wt.%)Si–1Al alloys

After combined additions of Sr and Sb, most primary Mg2Si crystals in Mg–3.5Si–1Al and Mg–5Si–1Al alloys transformed from equiaxed-dendritic shapes to octahedral morphologies; while eutectic phases also changed from Chinese script to short rod-shapes. The mechanisms of complex modification of Sr and Sb were attributed to the heterogeneous nucleation of primary Mg2Si on Sr11Sb10 nucleus, together with change in growth manners caused by incorporation of Sb in Mg2Si crystals.