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

► The Sr11Sb10 is the heterogeneous nucleation of primary Mg2Si in Mg-3.5Si-1Al alloys. ► Some Sb atoms were incorporated by substituting Si which changed growth manners of primary Mg2Si. ► Primary Mg2Si transformed from equiaxed-dendritic to octahedral after modification. ► Eutectic phases changed from Chinese script to short rod-shapes after modification.