Kinetics of segregation formation in the vicinity of edge dislocation in fcc metals

TL;DR

This paper investigates how strain fields around edge dislocations influence impurity atom segregation in fcc metals, using new diffusion equations and multilevel simulations to reveal complex impurity distribution behaviors.

Contribution

It introduces new equations for impurity diffusion fluxes under strain and combines molecular static modeling with nonlinear diffusion simulations for the first time.

Findings

Interstitial distributions near dislocations are complex

Vacancy and carbon distributions differ qualitatively

Strain significantly affects impurity segregation patterns

Abstract

We use new equations for the interstitial impurity diffusion fluxes under strain to study impurity atom redistribution in the vicinity of dislocations. Two levels of simulation are applied. The first one is evaluation of coefficients that determine the influence of strain tensor components on interstitial diffusion fluxes in FCC structures. For this purpose we have developed a model into the framework of a molecular static method taking into account an atom environment both near the interstitial site and for the saddle-point configuration. The second level is modeling the interstitial segregation formation based on nonlinear diffusion equations that take strains generated by defects into account. The results show that the distributions of the interstitials near the dislocations have quite complicated characters and the vacancy distribution has a qualitatively different character as compared with the carbon distribution.