The annealing kinetics of vacancies in finite monolayer patches containing several thousand particles were studied by using molecular dynamics techniques and three different central force interactions. The latter were: the nearest-neighbour piecewise linear force potential, the Lennard-Jones potential and the similar, r-8-r-4, potential. The simplest behaviour which was observed was the diffusion of vacancies to the nearest basins of attraction. These were edges, or larger concentrations of vacancies; leading, in the latter case, to voids. The voids in turn migrated to the next attractor, thus forming larger voids until all of the vacancies were annealed. Rapid dislocation-mediated healing, which removed most of the vacancies (with the dislocations annealing out of the system), could be observed in the presence of long-range interparticle interaction. Mobile vacancies and pressure also favoured this phenomenon. Dislocation-mediated healing could occur well below the self-diffusion temperature for vacancies. A so-called void/dislocation-dipole reversible conversion was observed for some small vacancy clusters in systems which exhibited both annealing processes.

Vacancy Annealing Kinetics in Finite Monolayer Patches. Z.Zhou, B.Joos: Surface Science, 1995, 323[3], 311-22