The concentrations of various atomic defects were calculated within the framework of a grand canonical formalism for the ordered compound, FexAl1-x (B2 structure). The input parameters for the grand canonical formalism were determined by using  ab initio  mixed-basis pseudopotential theory in the local-density approximation. It was shown that the FexAl1-x was not a compound with pure antisite disorder, neither was it a compound with pure triple-defect disorder. It instead exhibited a hydride behavior in which vacancies on the Fe sub-lattice, and antisite atoms on both sub-lattices, appeared. The concentration of vacancies on the Al sub-lattice was negligible.

J.Mayer, C.Elsässer, M.Fähnle: Physica Status Solidi B, 1995, 191[2], 283-98