| Abstract: | The equations describing the development of inclusions of a foreign phase are obtained, as a rule, under the assumption of a steady concentration field [1–3] or velocity field [4–7]. This is justified only if the process relaxes rapidly to a steady development. However, for the majority of systems of practical importance — the ensemble of pores when powders are sintered or an ensemble of gas bubbles in a liquid — even the actual possibility of their steady evolution is far from obvious. The general development of an ensemble of inclusions is associated with successive solution of the smallest of them with subsequent precipitation of the dissolved particles into the largest inclusions and into the exterior medium. Indeed, in the final stages of the process the particle fluxes are directed toward the exterior medium. It is clear that the complete process is strongly unsteady, since as it develops the directions and rates of molecular transport change. It is of interest to establish the conditions under which one can distinguish quasisteady stages characterized by the presence and persistence for an appreciable time of well-defined particle sources and sinks. Analysis of gas-liquid systems of simple configuration shows that steady regimes of their evolution are possible only if the liquid layer between the bubbles has a quite definite thickness. |
