An improved approach for obtaining thermodynamic descriptions of intermetallic phases: application to the Cr–Ta system

Some shortcomings of phenomenological phase diagram calculations are addressed in the present note: (i) the formalism currently used for describing ordered intermetallic phases and (ii) the criteria used for assessing the quality of a thermodynamic description. It is shown how the formalism used for ordered intermetallic phases can be improved by replacing the use of sublattice L parameters with a configurational independent term, which has its physical origin in the atomic size mismatch of the participating elements. It is also suggested that an examination of solid state phase diagrams provides an additional criterion for the acceptance of good thermodynamic descriptions over the criteria used at present. The Cr–Ta system is used as an example to show how this improved approach can be used to enhance the quality of the phenomenological thermodynamic modelling of ordered intermetallic phases.