A Constitutional Investigation of the Mo-Pd-Rh Ternary-System At 1100-Degrees-C

Abstract

Phase relations in the system Mo-Pd-Rh were studied at 1100-degrees-C using conventionally melted and ultrarapidly solidified samples. Optical microscopy, X-ray diffraction, scanning electron microscopy and electron probe microanalysis were used for phase characterisation. The complete isothermal section at 1100-degrees-C was established. The Mo bcc phase was found to have a very limited solid solution range whereas the ternary fcc solid solution originating on the Pd-Rh binary is the dominant phase in the system at this temperature. The centre of the isothermal is dominated by the ternary extension of the Mo-Rh hcp intermediate phase. The three phase (bcc + fcc + hcp) equilibrium region is located very near to the Mo-Pd binary system. No additional ternary intermediate phases were observed. The results are consistent with an isothermal section reported at higher temperatures.