(蘭州理工大學 甘肅省有色金屬新材料省部共建國家重點實驗室 蘭州 730050)
摘 要: 基于Wheeler模型和Eggleston修正強界面能各向異性的方法，建立耦合溶質場和溫度場的相場模型，模擬強界面能和界面動力學各向異性下Ni-Cu合金的枝晶生長過程。結果表明：兩種各向異性均顯著影響枝晶生長，在強界面動力學各向異性下，固相以類矩形方式沿á110ñ方向生長；在強界面能各向異性及同時存在兩種各向異性下，固相以枝晶方式沿á100ñ方向生長，界面方向不連續(xù)，枝晶臂主枝尖端出現(xiàn)棱角。在各向異性強度取值相同情況下，僅有界面能各向異性時，á100ñ方向枝晶尖端溫度梯度大，生長迅速，穩(wěn)態(tài)生長速度比同時存在兩種各向異性的大32.26%；僅有界面動力學各向異性時，á100ñ方向枝晶尖端溫度梯度小且溶質濃度高，生長緩慢，穩(wěn)態(tài)生長速度比同時存在兩種各向異性的小48.92%。
關鍵字: 二元合金；界面能各向異性；界面動力學各向異性；相場法；枝晶生長
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
