X-ray determination of the effect of temperature on the lattice parameters and the coefficients of thermal expansion of palladium-silver-gold alloys

Abstract

With a 19 cm Unicam high temperature powder camera, the precision lattice parameters and the coefficients of thermal expansion of three different compositions of Pd-Ag-Au ternary alloys have been studied at various temperatures ranging from room temperature to 899 °C by the X-ray method. It is found that, for all three alloys, the lattice parameter increases with increasing temperature. However, for all three alloys the variation of the coefficient of thermal expansion with temperature is found to be constant within the limits of experimental error. The composition dependence of the lattice parameter was also examined. The lattice parameter increases with decreasing palladium concentration, but shows a negative deviation from Vegard's law.