On the prismatic precipitate plates in Mg-Ca-In alloys

Prismatic precipitate plates in an age hardenable Mg-Ca-In alloy are characterized by atomic-resolution high-angle annular dark-field scanning transmission electron microscopy. The precipitate phase, designated δ, has a monoclinic structure. The proposed crystal structure of the δ is supported by first-principles calculations and multi-slice image simulations. The δ plates form with a considerably large dilatational strain in the direction perpendicular to their habit plane, and this strain is accommodated elastically.