Ab initio study of energy parameters in DO₃ phase of Fe-Al alloy

In the nonempirical approach based on the coherent potential approximation (CPA), we investigate the concentration dependence of the energy parameters which describe the stability of the disordered Fe-Al alloy and the phase transformation in B2 and DO₃ phases. We based our calculations on the most attractive feature of CPA to be applicable to the direct calculations of the electronic structure of random or partially ordered alloys. The procedure described in our study [D. Fuks and S. Dorfman, Solid State Commun. 90 773 (1994)] for the estimation of the parameters of the effective mixing potential is realized for different phases in the stoichiometric composition. Calculation data for different concentrations of Fe-Al alloy are used to extract the interaction parameters V(0), V(k₁), and V(k₂). These energy parameters are compared with the parameters treated from the diffuse X-ray scattering data. We show that the interaction parameters for Fe-Al alloys strongly depend on the concentration.