Phase-field modeling of rapid solidification

Rapid directional solidification under a constant thermal gradient was simu lated by a new phase-field model. The banded structures in an Al-Cu alloy w ere successfully reproduced. Only a few cells or dendrites survive in every transition steps into the plane-front mode, which explains the large grain size of banded structure observed in experiments. The noise level in conce ntration plays a crucial role in the transition procedure of the cell/dendr ite into the plane-front mode and so in the overall pattern formation of th e banded structure. (C) 2001 Elsevier Science B.V. All rights reserved.