Electronic Theory of Local Order

Abstract

The application of the perturbed free-electron approximation to a binary metallic solid solution leads to an expression for the energy which includes a term dependent on the local order. As a consequence of this term, and in the absence of other effects, short-range order is predicted for solid solutions with an electron/atom ratio of about one, and clustering for solid solutions with an electron/atom ratio between two and three. The sign and order of magnitude of the effect observed in several alloys where this approach may be appropriate is consistent with that calculated by this method.