An understanding of phase stability and its governing factors play a crucial role in alloy theory. It was shown that an inverse Heusler structure can generally gain stability through the configurational part of the entropy of mixing at elevated temperature without loosing too much enthalpy in the configurational part of the enthalpy of mixing owing to a special bond arrangement in the inverse type structure. This conclusion was derived from a general formula, which describes the ordering space for Heusler phases with general composition X2-xY1+xZ, an analysis of short and long bonds and the configurational entropy in the ordering space [1].
Figure 1: Different types of substitutional disorder (X,Y) for cubic Heusler structure of composition X2YZ. For each type of disorder the bcc tetrahedron is shown (left). Bond analysis of Mn2RuGe for disordered cubic Heusler-type structure.