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.