Kinetics of Heterogeneous Nucleation

Consider a phase transition α⇄β. Stable β-embryos can be retained in the temperature range of α-stability in cavities of suitable extraneous solids present in the system. Retained β-embryos may nucleate the α→β-transformation in the range of β-stability. Using these concepts a theory for the effect of thermal history upon the kinetics of phase transformations is proposed. The kinetics of heterogeneous nucleation in the absence of retained embryos is discussed.