The Huntington-McCombie-Elcock and anti-structure bridge mechanisms which had been proposed for B2 intermetallic compounds were reviewed. By using thermodynamic arguments, the former mechanism was shown to operate near to the stoichiometric composition. On the other hand, the other mechanism was shown to be important at compositions away from stoichiometry. A combination of these mechanisms was able to describe the compositional dependences of the experimentally determined self-diffusion coefficients for several B2 intermetallic compounds. It was further shown that the compositional dependences of the activation energies and pre-exponential factors were related to the partial molar enthalpies and entropies of the component elements. The frequently reported decreases in activation energy and pre-exponential factor, with deviation from stoichiometry, were judged to be in accord with corresponding decreases in the partial molar enthalpy and entropy.

C.R.Kao, S.Kim, Y.A.Chang: Materials Science and Engineering A, 1995, 192-193, 965-79