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

A Monte Carlo simulation study of the vacancy-assisted domain growth in asy mmetric binary alloys is presented. The system is modeled using a three-sta te ABV Hamiltonian which includes an asymmetry term. Our simulated system i s 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 dramaticall y. Concerning the asymptotic behavior it is algebraic and characterized by the Allen-Cahn growth exponent x = 1/2. The late stages of the evolution ar e preceded by a transient regime strongly affected by both the temperature and the degree of asymmetry of the alloy. The results are discussed and com pared to those obtained for the symmetric case. [S0163-1829(99)09329-7].