ON THE PROBLEM OF HIGH-RATE REACTIVE DIFFUSION

Competitive mechanisms for fast diffusional growth of an interphase la yer during the initial stage of reactive diffusion were analysed. The effect of fast growth is attributable to grain boundary diffusivity an d/or accelerated volume diffusion due to vacancy supersaturation. In a nalysing the latter case, vacancy source movement and the space distri bution of non-equilibrium vacancies were considered. The system parame ters which determine the governing mechanism of the process were obtai ned. It was shown that if, due to vacancy supersaturation, bulk diffus ion dominates, the process is intensified by the grain boundary diffus ion. (C) 1998 Elsevier Science S.A.