Pressure effect on ternary phase diagrams: Bi-Sb-Pb as a case study

Pressure can affect phase diagrams significantly, as previously demonstrated on several binary systems. However, the effect of pressure on ternary phase diagrams is mostly unexplored. In this study, a thermodynamic model of a ternary phase diagram under high pressure is formulated and applied to calculate the Bi-Sb-Pb system. The model employs binary interaction parameters and elemental thermodynamic functions to which the effect of pressure on the binary interaction parameters and elemental properties are added. The complete ternary Bi-Sb-Pb phase diagram was calculated up to a pressure of 2 GPa at selected temperatures as a case study, as this system involves three different types of binary phase diagrams: isomorphous, eutectic, and peritectic. The results show how pressure affects the stability of solid phases, leading to changes in the three-phase triangles and the four-phase equilibrium quadrilateral. This study provides insights into the pressure-dependent behavior of ternary systems and contributes to the thermodynamic understanding of ternary phase diagrams under high-pressure conditions.