Evolution of perimeter fraction during a phase transformation

Analytical expressions are obtained for the temporal evolution of the perim eter fraction during a phase transformation for both site-saturated nucleat ion and nucleation at a constant rate. In the former case, these expression s are then validated by a direct comparison with the results of two-dimensi onal computer simulations of nucleation and growth to impingement. Finally, the role of the evolving perimeter fraction on the energetics of transform ing systems is discussed. (C) 2000 Acta Metallurgica Inc. Published by Else vier Science Ltd. All rights reserved.