Pressure effects on alloy phase diagrams

The phase diagrams of binary alloys have been found to vary with pressure. Within the framework of solution-type models, the variation is controlled by the pressure dependence of the elemental end members, which is relatively well known, and that of the excess interaction, which is relatively unknown. Exact thermodynamic relationships for the pressure and temperature dependence of the interaction parameters in an alloy solution are developed and related to the composition dependence of the excess thermodynamic quantities measured at ambient conditions. The effects of pressure modification of selected phase diagrams, including transformation from isomorphous to eutectic forms and shifts of the eutectic point are explored. Model predictions are compared with experimental data.