- We carried out calculations of the thermodynamic factor Ω entering the Darken equation for interdiffusion. Ω is expressed in terms of the energy parameters which describe the ordering process in the binary alloy. Our calculations for Fe-Al alloys show the dependence of Ω on the long-range order parameter. These calculations are performed with the parameters extracted from the diffuse α-ray scattering data on FeAl. We emphasize the influence of the concentration dependence of energy parameters on Ω for different temperatures in our calculations.