A NEW APPROACH TO THE KINETICS OF A PHASE-TRANSFORMATION WITH CONSTANT RADIAL GROWTH-RATE

A new approach to the kinetics of a phase transformation with constant radial growth rate has been adopted which is based on the analogy bet ween the phase transformation and the process of continuous coverage o f space by overlapping spherical regions. A general kinetics equation has been derived with wider applicability than the classical Johnson-M ehl kinetics equation. The latter can be regarded as an approximation of the general kinetics equation proposed. when the nucleation rate is constant and the growth rate is small. Equations; independent of the shape and size of the covering objects, have been proposed to determin e the volume Fraction of the covered region during discrete and contin uous coverage. Copyright (C) 1996 Acta Metallurgica Inc.