Abstract:
Formation of nuclei of a new phase from supersaturated, or supercooled, mother phase (vapor-liquid, liquid-solid and vapor-solid phase transition) is studied at various conditions within standard nucleation model. Basic kinetic equations describing the time evolution of the size distribution of nuclei are solved numerically. Basic characteristics of nucleation process are determined, such as nucleation rate, time delay and the total number of nuclei formed in considered system. Two specific cases are considered: nucleation in closed systems and nucleation on active centers. In closed systems the number of particles in supersaturated mother phase decrease during new phase formation, which leads to decrease of supersaturation of mother phase. It has consequences to nucleation process itself. Active centers (dusty particles, impurities, ions, defects) are often presented in various systems and that is why this process occurs probably most often. Up to this time Avrami model including exhaustion of active centers is used. Our approach based on standard kinetic equations shows that Avrami model gives too fast exhaustion of active centers.