Thermodynamic factor in interdiffusion in Fe-Al alloys from the diffuse X-ray scattering

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