Application of recipes for isothermal and isochronal solid-state transformations

Departing from nucleation, growth and impingement mode occurring upon isothermal and isochronal solidstate transformations, several recipes, derived from (e.g. experimentally determined) transformed fraction and transformation rate, to deduce the growth exponent, n, and the effective activation energy, Q, have been examined, on the basis of an analytical phase transformation model. For solid-state transformation assuming site saturation or continuous nucleation, recipes derived from both transformed fraction and transformation rate can be used to deduce reasonable values for n and Q. For transformations assuming mixed nucleation, only recipes derived from transformed fraction are applicable. All the above recipes will give physically realistic values for n and Q, when the impingement mode holds constant upon changing the annealing temperature or the heating rate. These results have been tested using numerical calculations.