High-resolution electron microscopy observations of the interface structure of continuous precipitates in a Mg-Al alloy and interpretation with the O-lattice theory

The continuous precipitation of the β b.c.c. phase in Mg-Al gives rise to elongated platelets which exhibit a Burgers orientation relationship and whose habit plane is parallel to the matrix basal plane. The habit plane is found to contain a periodic array of secondary edge dislocations. It is shown that the epitaxial relationship, the growth direction and the interfacial structure can be interpreted by applying the CSL/DSC and O-lattice models.