Phase-field modeling of rapid solidification

Rapid directional solidification under a constant thermal gradient was simulated by a new phase-field model. The banded structures in an Al–Cu alloy were 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 concentration plays a crucial role in the transition procedure of the cell/dendrite into the plane-front mode and so in the overall pattern formation of the banded structure.