The morphology and crystallography of polygonal Mg2Sn precipitates in a Mg–Sn–Mn–Si alloy

The morphology and orientation of polygonal Mg2Sn precipitates in a Mg–Sn–Mn–Si alloy were characterized using transmission electron microscopy. The precipitates exhibit four pairs of facets. While three pairs of them are not parallel to any low-indexed plane, each facet is normal to particular Δg’s. Based on a detailed constrained coincidence site lattice and mismatch analysis of the structures in the interfaces, the orientations of these facets can be explained in terms of a relatively high density of near-coincident site lattice points.