Isothermal sections of the Au-In-Pd system at 500 and 800 °С

Abstract

Partial isothermal sections of the Au-In-Pd system at 500 and 800°С for indium content less than 50 at.% have been plotted using electron microscopy, XRD and EDX methods. The boundaries of FCC solid solution in the system at these temperatures and the solubility of the third components in the compounds of the In-Pd and Au-In boundary binary systems have been determined. Three new ternary compounds τ1, τ2 and τ3 have been found at 500°С. The τ1 compound has cubic Cu3Au-type structure, the τ2 compound has tetragonal AuCu-type structure, and the τ3 compound has hexagonal CaHg2-type structure. The unit cell parameters of the τ2 and τ3 phases have been refined by Rietveld method, and the distribution of atoms over crystallographic positions in their structures has been studied. At 800°С, the τ1 compound has wider homogeneity range for gold than that at 500°С. The τ2 compound at 800°С exists in a narrow range, and the τ3 phase is not stable at this temperature.