We study a lattice gas model for a binary alloy with vacancies by means of a mean-field kinetic equation. Simulations of droplets of unstable mixture immersed in a stable vapor show the emergence of ordered structures at the surface which propagate into the bulk. We calculate characteristic wavelengths and propagation velocities of these patterns by a linear stability analysis. The thickness of the ordered layer depends on the model parameters and the strength of the initial noise.

• Received 28 January 1997

DOI:https://doi.org/10.1103/PhysRevLett.78.4970