共晶形态层—棒转变的多相场法研究

利用KKSO多相场模型研究了不同抽拉速度及不同液相溶质扩散系数条件下共晶形态层—棒状转变过程. 模拟结果表明：在抽拉速度较低时，层片共晶首先发生合并现象，然后继续以层片形态生长；增大抽拉速度，发生层片合并后共晶形态由层片向棒状转变；进一步增大抽拉速度，层片不发生合并，仅以初始层片间距进行稳态层片生长. 溶质扩散系数条件的改变同样会导致共晶形态发生层—棒状转变，结果还表明层—棒转变仅在一定参数范围内发生. 模拟结果与实验研究定性符合. 关键词： 层—棒转变 多相场 数值模拟

An investigation of the lamellar-rod transition in binary eutectic using multi-phase field model

The KKSO multi-phase field model is employed to simulate the lamellar-rod transition with different pulling velocities and different solute diffuse coefficients in liquid. The simulation results show that the eutectic keeps lamellar growth after lamellar merging at small pulling velocity. With an increase of the pulling velocity, the lamellar eutectic transits to rod-like eutectic after lamellar merging. And the further increase of the pulling velocity will make the lamellar grow steadily with its initial lamellar spacing. It's also found that the simulations of different solute diffusion coefficients in liquid are similar to those of different velocities and the transition from lamellar eutectic to rod-like takes place only in a certain range of each parameter. All of the simulated results are in agreement with the experiments qualitatively.