The Pressure-Volume Relation and Cohesive Properties in Transition Metal Alloys

Abstract

A method to treat the pressure-volume relation in alloys on the basis of the virial theorem is proposed, and then the lattice parameter, the bulk modulus and the formation energy of the disordered 4d transition metal alloys are calculated. In this calculation, the s-d hybridization is neglected and the d band is treated in the single band off-diagonal C.P.A, the s band in the free electron like rigid band model. Assuming the charge neutrality condition at each site, it is found that the calculated lattice parameters, bulk moduli and formation energies of Nb–Zr alloy and Pd-base 4d transition metal alloys agree with the observed trends. Particularly, it is found that the negative deviation from the Vegard law is mainly due to the d part pressure. The origin of this attractive pressure lies in the gain of the Pd-site bond energy due to alloying.