A Computer Assessment of the Ternary Ru-Rh-Pd System

Abstract

Thermodynamic coefficients of the phases in the binary Ru-Rh, Pd-Rh and Ru-Pd systems were derived by assessment of the available experimental data using the binary Lukas optimization program. The resulting coefficients were first successfully utilised in re-establishing the binaries. The coefficients thus established in the binary computation were combined with binary descriptions to compute ternary isothermal sections. Although no ternary interaction term was involved in the construction of the isotherms, the calculation at 1973 K is found to be consistent with the experimentally established isothermal section at the same temperature. The location of three-phase fields (liquid + hcp + fcc) and phase boundaries in both isotherms are matching reasonably well and these show that that ternary interactions of the components in these phases are less strong. 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 973 to 2473 K of the ternary Ru-Rh-Pd system were calculated.