The correlation between the interaction energies used in a nearest-neighbour mean-field model, and the vacancy concentrations in B2 intermetallic alloys, was examined. The range of vacancy behaviors was classified into 4 generic categories. In particular, a condition on interaction energies was derived under which the alloys contained constitutional vacancies. Existing theoretical results were analyzed within the framework of the present classification scheme, and were rationalized by using the interaction energies used in those studies. Because differing sets of interaction energies could predict the same vacancy behavior, it was concluded that experimental verification should use not only measurements of the vacancy concentration, but also measurements of other point defects. An examination of the relative atomic size of B in comparison with the nearest-neighbour distance in the B2 structure revealed that it could be an important reason why the aluminides contained constitutional vacancies.

Effect of Interaction Energies on the Vacancy Behaviour in B2 Ordered Intermetallics. M.P.Gururajan, T.A.Abinandanan: Materials Science and Engineering A, 2002, 329-331, 388-94