Multi-phase field simulation of unidirectional solidification for binary eutectic alloys

The unidirectional solidification process of a binary eutectic model alloy at low Peclet number was simulated by multi-phase field method together with moving box algorithm. The selection mechanism of lamellar spacing was also studied. The simulation results show that, when the initial lamellar spacing is smaller than that under the minimal undercooling theory, to restabilize the lamellae growth, the annihilation of lamellae occurs; on the contrary, new phase at the top of lamellae nucleates. Moreover, the eutectic period-preserving oscillatory instability (1λ oscillatory) is recurred, which results from the solute redistribution and the volume adjustment of two eutectic phases.