Modeling of ternary site occupation in L12 ordered intermetallics

The site preference of ternary additions in an A₃B intermetallic compound with the L1₂ structure is modeled using the tetrahedron approximation of the Cluster Variation Method. At T = 0 K, there are three fundamental site preference behaviors for the ternary additions, depending on the relative magnitude of the effective pair interactions. It is found that the site preference of the ternary element is generally not related to the direction of the L1₂ solubility lobe. Our model also indicates that, under some conditions, the site preference can change with alloy composition and with temperature.