The cluster variation method, widely used for solving problems of phase equilibrium in metals and alloys, was extended here to calculations of the energy and profile of antiphase boundaries in the intermetallic compounds such as Ni-Al-X systems (X was chosen to be Fe). The site preference of ternary elements in the relaxed (111) antiphase boundary region for L12-type Ni3Al(X) alloys was calculated, based upon the tetrahedron approximation of the cluster variation method. It was found that the peak of the calculated (111) antiphase boundary energy appeared at an alloy composition deviating slightly to the Al-rich side of stoichiometry. This deviation was considered to result from the short-range effect between Ni and Al at the antiphase boundary region.

Site Preference of Atoms in the Relaxed (111) APB of Ni3Al(X) Alloys. Shinoda, T., Masuda-Jindo, K., Mishima, Y.: Journal of Phase Equilibria, 1998, 19[6], 552-8