Effect of discretization and finite nuclei radius on Kolmogorov-Johnson- Mehl-Avrami isothermal kinetics: A 2-dimensional study

Abstract

The Kolmogorov-Johnson-Mehl-Avrami (KJMA) isothermal phase transformation kinetics theory assumes negligible volume of the nucleus. For systems with nano-sized grain formation, the initial introduction of finite radius of the product phase nuclei has special relevance. The value of time exponent deviates from the ideal KJMA prediction for such cases. Discrete models may be advanced for explaining such deviation. The main limitation of such an approach is the discrete time step used. We have recently studied these aspects of isothermal transformation kinetics in a systematic way with the help of discrete adaptation of KJMA model. The transformation is assumed to be polymorphic and interface controlled. In this paper we present studies on 2-dimensional (2D) systems.