Crystallogeometry and energy of planar superstructure defects of ternary alloys

Planar superstructure defects have a great influence on the mechanical and functional properties of ternary Heusler alloys; however, their complete crystallogeometric and energy analysis is lacking in the literature. In this work, Heusler alloys of stoichiometric composition X2YZ of the L21 superstructure are analysed. An expression is given for finding the planes of occurrence of all possible planar superstructure defects. It is established that among them there are only shear and thermal antiphase boundaries. The results obtained are useful for analyzing slip systems of the considered family of alloys and the configuration of magnetic domain walls.