Order?Disorder Transformations in Alloys. The Inclusion of Non-nearest Neighbour Interactions in Cluster Variation Methods. I. Critical Temperature and High Temperature Specific Heats for Body Centred Cubic Lattices

Abstract

The Sanchez and de Fontaine formulation of the cluster variation method is used in a study of order-disorder phase transformations in a body centred cubic (b.c.c.) lattice. The method is modified to include second neighbour interactions in the configurational energy term. The dependence of the critical temperature on the ratio a of second neighbour to nearest neighbour interaction energy is studied. The method is also used to study. the dependence of the high temperature specific heat on a. It is found that the sign and magnitude of a have a marked effect on both of these properties.