Phenomenological Investigation of Disorder-L1, Phase Equilibria for Au-Pd and Ni-Pt Alloy Systems

Abstract

A phenomenological investigation is performed on the disorder-Ll o phase equilibria for Au-Pd and Ni-Pt alloy systems based on the Lennard-Jones type pair potential combined with thermal vibration effects and the Cluster Variation Method. The phase diagrams are calculated and relevant thermodynamic quantities such as long range order parameters and thermal expansion coefficients are derived. It is revealed that the thermal vibration effects decrease the order-disorder transition temperature, which is attributed to the destabilization of the Ll o ordered phase due to the enhancement of the disordering reaction caused by the lattice softening