A Computer Calculation of the Ternary Mo-Pd-Rh Phase-Diagram

Abstract

Thermodynamic coefficients for the phases in the binary Mo-Pd, Pd-Rh and Mo-Rh systems were derived by the assessment of the available experimental data using the binary Lukas optimization program. The resulting coefficients were first successfully utilised in reestablishing the binaries. The coefficients thus obtained in the binary computation were combined with ternary descriptions to compute ternary isothermal sections. Although no ternary interaction term was involved in the construction of the isotherms, the section calculated at 1373 K is found to be consistent with the experimentally established isothermal section at the same temperature. The location of three-phase field (bcc+hcp+fcc) and phase boundaries in both isotherms are matching reasonably well. Combining only binary coefficients of these phases, it is possible to construct reasonable isothermal sections at different temperatures. Following this conclusion, isothermal sections ranging from 1373 to 2673 K of the ternary Mo-Pd-Rh system were calculated.