Application of thermal analysis methods to nucleation and growth transformation kinetics, Part II

The general theory of transformation kinetics is largely confined to isothermal reactions. Several attempts have however been made to apply that theory to non-isothermal nucleation and growth transformations as well. Unfortunately, this has lead to some confusion and misunderstandings when thermal analysis experiments, such as DSC and DTA, associated with Kissinger- or Ozawa-like relationships, are used for the extraction of the kinetic parameters of the non-isothermal transformations. The present Part II of this paper widens the scope of the discussed issues, assesses the correct way of applying the theory of isothermal kinetics to non-isothermal transformations, stresses the sources of confusion and points to the mathematical and physical errors that commonly appear in the literature. It is shown that only 'site saturated' transformations, i.e. those where the nucleation rate is zero, can be properly analyzed. The general non-isothermal equation for the fraction transformed is proven to be the sound and sole foundation for the correct deduction of the transformation kinetic parameters.