Analysis of solid state phase transformation kinetics: models and recipes

The progress of solid-state phase transformations can generally be subdivided into three overlapping mechanisms: nucleation, growth and impingement. These can be modelled separately if hard impingement prevails. On that basis, an overview has been given of recent numerical and analytical methods for determination of the kinetic parameters of a transformation. The treatment focuses on both isothermally and isochronally conducted transformations. To extend the range of transformations that can be described analytically, a number of more or less empirical submodels, which are compatible with experimental results, has been included in the discussion. It has been shown that powerful, flexible, analytical models are possible, once the concept of time or temperature dependent growth exponent and effective activation energy, in agreement with the existing experimental observations, has been adopted. An explicit (numerical) procedure to deduce the operating kinetic processes from experimental transformation-rate data, on the basis of different nucleation, growth and hard impingement mechanisms, has been demonstrated. Without recourse to any specific kinetic model, simple recipes have been given for the determination of the growth exponent and the effective activation energy from the experimental transformation-rate data.