(兰州理工大学 甘肃省有色金属新材料省部共建国家重点实验室 兰州 730050)
摘 要: 基于Wheeler模型和Eggleston修正强界面能各向异性的方法，建立耦合溶质场和温度场的相场模型，模拟强界面能和界面动力学各向异性下Ni-Cu合金的枝晶生长过程。结果表明：两种各向异性均显著影响枝晶生长，在强界面动力学各向异性下，固相以类矩形方式沿á110ñ方向生长；在强界面能各向异性及同时存在两种各向异性下，固相以枝晶方式沿á100ñ方向生长，界面方向不连续，枝晶臂主枝尖端出现棱角。在各向异性强度取值相同情况下，仅有界面能各向异性时，á100ñ方向枝晶尖端温度梯度大，生长迅速，稳态生长速度比同时存在两种各向异性的大32.26%；仅有界面动力学各向异性时，á100ñ方向枝晶尖端温度梯度小且溶质浓度高，生长缓慢，稳态生长速度比同时存在两种各向异性的小48.92%。
关键字: 二元合金；界面能各向异性；界面动力学各向异性；相场法；枝晶生长
binary alloy with strong anisotropy
（State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050, China）
Abstract:Based on the Wheeler model and the Eggleston regularization technique of strong anisotropy of interface energy, the phase-field model was built by coupling with the concentration field and temperature field. The dendrite growth process of Ni-Cu alloy with strong surface energy and kinetic anisotropy were simulated. The results show that the dendrite growth depends on the two kinds of anisotropies. Under the strong surface kinetic anisotropy condition, the melt solidifies grow along the á110ñ orientation and the crystals grow into a square-like. Under the strong surface energy anisotropy or having two kinds of anisotropies condition, the melt solidifies in a dendrite pattern grow along the á100ñ orientation and the variation of interface orientation discontinuity can lead to the corners form on the tip of dendrite. In the case of anisotropy strength with the same values, under the strong surface energy anisotropy condition, the thermal gradient along the á100ñ orientation is large, and makes the dendrite growth become fast, the tip velocity at steady state increases by about 32.26% compared with the case that having two kinds of anisotropies. Under the strong surface kinetic anisotropy condition, the thermal gradient along the á100ñ orientation is small and the concentration of solute is large, and makes the dendrite growth become slow, the tip velocity at steady state decreases by about 48.92% compared with the case that having two kinds of anisotropies.
Key words: binary alloy; surface energy anisotropy; surface kinetic anisotropy; phase-field; dendrite growth
