Application of cluster models in the theory of phase diagrams and short-range order in alloys

Cluster techniques used in microscopic theories of ordering and of short-range order in alloys, that is: technique of cluster variations (TCV), where some correlations are mentioned, as well and technique of cluster fields (TCF) which represent simplified technique, which is very close concerning its accuracy to TCV convinient for applications and correlations - are described. Applications of TCF concerning analysis of data on short-range order which allow to determine configuration potentials for some alloys and their quality pecularities, in particular, concentration dependence and odd force contributions are described. Accuracy of different approximations of TCV and TCF when describing phase diagrams is studied using calculations for L12 and L10 type orderings in fcc-alloys as an example Ni-Fe phase diagram calculated according to short-range order data agrees well with experimental one