The thermodynamics of point defects in an ordered AmBn alloy were considered for the case of small deviations from the stoichiometric composition. The concentrations of the 2 types of antisite and vacancy were functions of 3 basic energies of formation, and of the stoichiometry. General formulae for these were derived which could be solved numerically. Analytical formulae for the chemical potentials were derived in terms of the point-defect concentrations. Simple analytical formulae were also derived, for the concentrations, which were valid when the constitutional defects (which predominated at low temperatures) continued to predominate over thermally excited defects of the same type at higher temperatures. The energies which appeared in these formulae were defined in a general way which was suitable for  ab initio  or semi-empirical methods of calculation. The results were illustrated, for the case of NiAl, by using 3 different N-body central potentials. A significant effect was shown to arise from the temperature dependence of the formation energies.

Point Defects and Chemical Potentials in Ordered Alloys M.Hagen, M.W.Finnis: Philosophical Magazine A, 1998, 77[2], 447-64