Thermodynamic modeling of the Cr–Hf–Si System

A thermodynamic description for the Cr–Hf-rich region of the Cr–Hf–Si system has been developed on the basis of the constituent binary systems, and critically reviewed ternary experimental information, using the CALPHAD approach. The published thermodynamic descriptions for the Cr–Si and Hf–Si binary systems were directly used; the thermodynamic description for the Cr–Hf binary system was modified in the present study. The ternary interaction parameters were optimized using EPMA measurements on the solid-state phase equilibria at 1200 °C, DTA measurements for the Cr–63Hf–4Si alloy, and liquid–solid reaction information extracted from as-cast microstructures of the metal-rich Cr–Hf–Si alloys. Comparisons between the calculated results and the experimental measurements show that the new model developed in the present study can satisfactorily describe the metal-rich region of the Cr–Hf–Si ternary phase diagram.