二元合金等轴枝晶生长相场模拟

在传统纯物质相场模型的基础上，对其中的体系自由能进行重新构造，得到一个紧密联系相图且综合考虑了传热、溶质扩散、界面能各向异性和界面动力学各向异性等适用于二元合金枝晶生长的新相场模型，并利用该模型结合一种能显著提高计算效率的“临界面点相场大梯度计算域控制法”，对AJ-7Si合金在初始过冷度分别为35K和50K的过冷熔体中等轴枝晶生长进行了模拟，得到许多与试验观察相符合的结果；同时在枝晶生长过程中跟踪枝晶主轴尖端，获得其尖端半径和尖端速率，发现随着凝固时间的增加，逐渐收敛，直到枝晶达到稳定生长，而且通过简化KGT模型计算的枝晶尖端的生长速率与模拟值相近。另外，就过冷度对等轴枝晶生长的影响进行了分析。

Phase Field Simulation of the Growth of Equiaxed Dendrite for Binary Alloy

By reformulating the free energy of a system, a new phase field model is derived from closely associating the alloy phase diagram and comprehensively considering the heat transfer, solute diffusion, the anisotropy of interface energy and interface kinetics. Then the equiaxed dendritic growth of Al 7Si alloy in a undercooling melt 35 K and 50 K respectively is simulated using the new phase field model in combination with critical point plane phase field with large gradient calculation area government method that can improve calculating efficiency significantly. The some simulated results in agreement with the experimenttal resaets can be obtained. The traced tip velocities and the tip radiuses of the primary dendrite are derived from the dendrite growth process. In addition, the values of the tip velocity obtained from the simulation are in agreement with those calculated by the KGT model.