  The influence of diffusing vacancies on the antiphase domain growth process
in a binary alloy is studied by Monte Carlo simulations. The system is modelled
by means of a Blume-Emery-Griffiths hamiltonian with a biquadratic coupling
parameter K controlling the microscopic interactions between vacancies. We
obtain that, independently of K, the vacancies exhibit a tendency to
concentrate on the antiphase boundaries. This gives rise to an effective
interactions between movin interfaces and diffusing vacancies which strongly
influences the domain growth process. One distinguishes three different
behaviours: i) for K<1 the growth is anisotropic and can be described by
algebraic laws with exponents lower than 1/2, ii) for K=1 we find standard
Allen-Cahn growth and iii) for K>1 the growth is slown down but still curvature
driven.
