Evolution of penny-shaped microcracks by interface migration

An axisymmetric finite element method is developed and employed to simulate healing evolution of intragranular penny-shaped microcracks under interface migration driven by total free energy change consisted of surface tension and chemical potential difference between phases. The validity of the method is confirmed by an agreement of the shrinkage and growth behavior, simulated numerically, of an isolated spherical grain with those predicted theoretically. The results showed that the surface tension alone serves to evolve the initial penny shape to a spherical one and, coupled with the chemical potential difference, dominates volume shrinkage of the microcracks. As the initial aspect ratio of a microcrack increases, both spheroidization and volume shrinkage times increase continuously. And the volume shrinkage process of the microcracks can be greatly promoted with an increase in the chemical potential difference.