Vacancy-assisted domain-growth in asymmetric binary alloys: a Monte Carlo study

TL;DR

This study uses Monte Carlo simulations to investigate how vacancies influence domain growth in asymmetric binary alloys, revealing slower ordering and algebraic growth characterized by the Allen-Cahn exponent, with transient regimes affected by temperature and asymmetry.

Contribution

Introduces a three-state ABV Hamiltonian including asymmetry, providing new insights into vacancy-assisted domain growth in asymmetric alloys compared to symmetric cases.

Findings

Ordering slows down significantly in asymmetric alloys.

Asymptotic growth follows an algebraic law with exponent 1/2.

Transient regimes are influenced by temperature and asymmetry degree.

Abstract

A Monte Carlo simulation study of the vacancy-assisted domain-growth in asymmetric binary alloys is presented. The system is modeled using a three-state ABV Hamiltonian which includes an asymmetry term, not considered in previous works. Our simulated system is a stoichiometric two-dimensional binary alloy with a single vacancy which evolves according to the vacancy-atom exchange mechanism. We obtain that, compared to the symmetric case, the ordering process slows down dramatically. Concerning the asymptotic behavior it is algebraic and characterized by the Allen-Cahn growth exponent x=1/2. The late stages of the evolution are preceded by a transient regime strongly affected by both the temperature and the degree of asymmetry of the alloy. The results are discussed and compared to those obtained for the symmetric case.