A kinetic model for electromigration in face-centred cubic alloys

Abstract

A detailed microscopic understanding of electromigration processes in alloys is still lacking. This study is intended to analyse the atomic fluxes in dilute substitutional alloys with electromigration driving forces. The five-frequency model, developed for the description of diffusion via the single-vacancy mechanism in dilute alloys, is applied here for the study of electromigration. The model is generalized to a case in which an alloying atom changes the electromigration driving force on surrounding host atoms. For some choices of parameters the atomic fluxes deviate from expressions found in the literature. Analysis and kinetic Monte Carlo simulation of some limiting cases confirm the new expressions. The properties of the flux equations are studied in detail for several interesting cases. In particular, it is shown that the addition of a few atomic per cent of alloying atoms can reverse the direction of the flux of host atoms under certain conditions. Such a mechanism can slow down electromigration mass transport and could therefore be of great technological importance for the development of electromigration-resistant alloys.