中文摘要：

采用有限差分法求解考虑界面能各向异性的相场模型，对镁合金枝晶生长过程进行了模拟计算，研究了无量纲过冷度和各向异性强度对枝晶生长行为的影响。结果表明：镁合金枝晶在二维平面上具有6个最优生长方向，优先生长方向上枝晶生长迅速，形成枝晶主干，枝晶形貌具有六重对称性。随着过冷度和各向异性强度的增加，枝晶形貌由光滑的类六边形向具有侧向分支的六重对称形貌转变，温度扩散层由类球形向犀形主十溏．桔品尖端毕长辣率增加．尖端曲率半径和濡唐值减小。

英文摘要：

The phase field model taken into account the interfacial energy anisotropy has been used to simulate the dendrite growth of magnesium alloys by the finite difference method.The effects of dimensionless undercooling and the anisotropy strength on the dendrite growth behavior have been studied. The results showed that the six preferential growth orientations of dendrite of magnesium alloys existed in the two dimensional XY-plane,the dendrite grew fast and developed to the dendrite trunks at the preferential growth orientation,the dendrite morphology showed sixfold symmetry.With the increasing of undercooling and anisotropy strength,the dendrite morphology changed from smooth quasi-hexagonal to the sixfold symmetry dendrite with side-branches,the thermal diffusion layer turned from near- spherical shape to star,the dendrite tip velocity inereased while radius in the tip and temperature decreased.