强界面能各向异性下二元Ni-Cu合金枝晶生长过程的相场法模拟  

Phase-field simulation of dendrite growth process for binary Ni-Cu alloy with anisotropy of strong interface energy

作　　者：袁训锋[1] 丁雨田[1] 

机构地区：[1]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

出　　处：《中国有色金属学报》2011年第7期1656-1663,共8页The Chinese Journal of Nonferrous Metals

基　　金：兰州市科技局资助项目(2009-1-9);兰州理工大学博士基金资助项目(SB01200606)

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,模拟强界面能各向异性下Ni-Cu合金枝晶生长过程。结果表明:在强界面能各向异性作用下,界面方向枝晶生长不连续且枝晶出现棱角;由于枝晶尖端温度梯度和溶质梯度较大,枝晶生长迅速。当界面能各向异性强度低于临界值时,枝晶尖端生长速度随界面能各向异性强度的增加而增大;当界面能各向异性强度等于临界值时,枝晶尖端生长速度下降4.34%;当界面能各向异性强度大于临界值时,枝晶尖端生长速度随界面能各向异性强度的增加先增大到极大值后逐渐减小。当无量纲热过冷度较小时,晶体平衡形貌为类矩形;随着无量纲热过冷度的增加,晶体平衡形貌向枝晶转变,枝晶尖端生长速度先呈幂指数增加,然后呈线性增加,枝晶生长由扩散控制转变为动力学控制。Based on the Wheeler model and the Eggleston regularization technique of the anisotropy of strong interface energy,the phase-field model was built by coupling the solute field with temperature field,and the dendrite growth process of the anisotropy of strong interface energy of Ni-Cu alloy was simulated.The results show that the variation of interface orientation discontinuous and the corners form on the dendrite with the anisotropy of strong interface energy,the dendrites grow fast due to the large temperature gradient and solute gradient.With an increase in anisotropy strength,the growth velocity of dendrite increases when the anisotropy strength is lower than the critical value;when the anisotropy strength equals the critical value,the growth velocity drops down by about 4.34%;with an increase again in anisotropy strength（larger than the critical value）,the growth velocity reaches the maximum value and then tends to decrease.The equilibrium morphology of the crystal grows into a square-like one in the situation of low dimensionless supercooling degree;with an increase in dimensionless thermal supercooling degree,the equilibrium morphology of the crystal changes from square-like to dendrite,the growth velocity of dendrite increases exponentially and then increases linearly,and the dendrite growth is under control from diffusion to kinetics.

关 键 词：Ni-Cu合金 界面能 各向异性强度 过冷度 相场法 枝晶生长 

分 类 号：TG146[一般工业技术—材料科学与工程]