An analysis of the distribution of defects in a two-stage tight binding model for Al-In alloys

Abstract

It has been shown previously that the isochronal recovery of dilute binary alloys of In in Al is consistent with the concept of a two-stage tight binding model which, in its simplest form, assumes the existence of single vacancies, isolated impurity atoms, bound mixed pairs, and triplets consisting of two vacancies and one impurity atom. The expressions relating the equilibrium concentrations of these defects are solved, and the two measured binding energies are used to calculate the distributions of defects as a function of total impurity and vacancy content of the alloy and of temperature. Comparison of the form of these calculated distributions with the pertinent isochronal recovery stages observed in dilute alloys of In in Al is quite satisfactory and, hence, is taken as supporting evidence that the model is a valid representation of dilute alloys of this and similar systems in which there is a strong interaction between vacancies and impurity atoms.