A pr 1 99 7 Effect of the vacancy interaction on the antiphase domain growth process in a two dimensional binary alloy

We have performed a Monte Carlo simulation study of the influence of diffusing vacancies on the antiphase domain growth process in a binary alloy after a quench through an order-disorder transition. The problem has been modeled by means of a Blume-Emery-Griffiths hamiltonian which biquadratic coupling parameter K, controls the microscopic interactions between vacancies. The asymmetric term L has been taken L = 0 and the ordering dynamics has been studied at very low temperature as function of K inside the range −0.5 ≤ K/J ≤ 1.40 (with J > 0 being the ordering energy). The system evolves according to the Kawasaki dynamics which conserves the alloy concentration while the order parameter does not. The simulations have been performed on a two-dimensional square lattice and the concentration has been taken so that the system corresponds to an stoichiometric alloy with small concentration of vacancies. We obtain that, independently of K, the vacancies exhibit a tendency to concentrate at the antiphase boundaries. This effect gives rise, via the vacancy-vacancy interaction (described by K), to an effective interaction between bulk diffusing vacancies and moving interfaces which turns out to strongly influence the domain growth process. One dis-