CHEMICAL AND MAGNETIC-INTERACTIONS IN FCC FE-NI ALLOYS USING THE CLUSTER VARIATION METHOD

The cluster variation method (CVM) has been widely used to model alloy systems involving chemical interactions but has had limited use with systems which are also magnetic. This paper presents a modified form of the CVM for an FCC alloy in the tetrahedral approximation which allows both chemical and magnetic interactions to be considered simultaneously. In addition the technique allows these interactions to be defined as directly dependent upon chemical composition. With this approach a theoretical coherent phase diagram is determined for the Fe-Ni system which compares favourably with the experimental diagram. The interaction parameters required are similar to those determined by other techniques.