The implications of vacancy-pair mechanisms for chemical diffusion in intermetallic compounds with the B2 structure were considered. The discussion specifically included the so-called triple-defect mechanism. It was shown that the vacancy-pair mechanism could not contribute to chemical diffusion in the intermetallic compound at the stoichiometric composition AB. Focusing on the triple-defect mechanism, it was extended to non-stoichiometric compositions by including isolated antistructural atoms. By means of Monte Carlo simulation it was shown that the efficiency of the triple-defect mechanism in providing for chemical diffusion increased linearly with increasing antistructural atom composition but the efficiency remained relatively low unless the composition was highly non-stoichiometric.

Chemical Diffusion by Vacancy Pairs in Intermetallic Compounds with the B2 Structure. G.E.Murch, I.V.Belova: Philosophical Magazine Letters, 2000, 80[8], 569-75