A cluster expansion for Cu-Au alloys based on experimental data

The calculation of effective cluster interactions (ECIs) from experimental data rather than from calculated total energies is described. The procedure is illustrated for Cu-Au alloys with the enthalpy of mixing for random alloys being calculated from experimental data for the ordered alloys. The cluster expansion formalism from which the ECIs are obtained could direct the conventional thermodynamic evaluation of phase diagrams to a physically more fundamentel viewpoint and, consequently, become an important new component to be considered in the CALPHAD-like assessments.