Thermodynamic assessment of the Pd–Y binary system

Abstract

The Pd–Y system was critically assessed using the CALPHAD technique. The solution phases (liquid, b.c.c., f.c.c. and h.c.p.) were modeled using the Redlich–Kister equation. The intermetallic compounds Pd3Y and PdY, which have homogeneity ranges, were treated as the formula (Pd,Y)0.75(Pd,Y)0.25 and (Pd,Y)0.5(Pd,Y)0.5 by a two-sublattice model with a mutual substitution of Pd and Y on both sublattices. The optimization was carried out in two steps. In the first treatment, Pd3Y and PdY are assumed to be stoichiometric compounds; in the second treatment they are treated by a sublattice model. The parameters obtained from the first treatment were used as starting values for the second treatment. The calculated phase diagram and the thermodynamic properties of the system are in satisfactory agreement with the experimental data.