If there are impurities in the liquid phase in the form of solid particles, then the crystallization often begins on them, as on finished substrates.
The role of such particles can play the walls of molds, non-metallic inclusions, oxides, etc. The foreign particles are active if the work of germs formation is less on them than the work of spontaneous generation of the germs. This is the case when the surface tension at the interface of the germ is an alien particle smaller than at the interface between the nucleus and the liquid phase. The interfacial energy is characterized by the wetting angle of the droplet of the mother phase on the Continue reading →