AVRAMI EXPONENTS FOR TRANSFORMATIONS PRODUCING ANISOTROPIC PARTICLES

The behavior of Avrami exponents (AE) for systems which produce anisot ropic particles (for which shielding effects and phantoms occur) is ex amined. Probabilistic arguments used in previous studies an applied to derive expressions for the AE as a function of time or the extent of transformation. Numerical calculations for the one dimensional (1D) ca ses of site saturation and continuous nucleation show that blocking ef fects produce a minimum in plots of AE versus extent of transformation . The influence of growth rate anisotropy upon the magnitude of the re duction in the AE is also examined and certain features of the behavio r of the AE for 2D and 3D systems are discussed.