相场法模拟热耦合强度对纯Ni枝晶生长的影响  

Phase-Field Simulation for Dendritic Growth Behavior of Pure Ni under Different Temperature Coupling Strength

作　　者：赵宇宏[1] 刘卫津 侯华[1] 

机构地区：[1]中北大学,山西太原030051

出　　处：《稀有金属材料与工程》2014年第4期841-845,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金资助(50975263;51204147;51274175);科技部国际合作资助项目(2011DFA50520);教育部博士点新教师基金(20101420120005)

摘　　要：基于Karma的薄界面极限相场模型,研究了相场和温度场耦合强度对过冷纯Ni熔体中枝晶生长行为的影响。模拟结果表明:随着热耦合强度的减弱,相场受温度场的影响作用减弱,固-液相界面前沿扰动变大,主枝出现二次枝晶并逐渐发达粗化,其粗化方式由缩颈熔断向枝晶臂合并方式转变。同时,枝晶尖端的生长速率增大、曲率半径减小。瞬态过程中枝晶尖端生长速度大于稳态生长速度,随着生长过程的进行,枝晶尖端生长速度逐渐降低,直至达到稳态值,计算结果与微观可解理论吻合良好。Based on the diffusion Karma phase field model with thin interface limit, the dendrite growth behavior of pure Ni undercooled melt was simulated under different temperature coupling strength. Results show that as the thermal coupling strength decreases, the impact of the temperature field on the phase field weakens, the solid-liquid interface disturbance increases, and secondary dendrites develop gradually from the main branch. Meanwhile, the dimensionless growth velocity of dendrite tip increases, while the dimensionless dendrite tip radius decreases. Furthermore, at the initial solidification stage, the transient growth velocity of dendrite tip is greater than the theoretical stable growth velocity; with the growth process going on, the growth velocity of dendrite tip gradually decreases until it equals to the theoretical stable value. Therefore, the computational results by the phase-field method are in good agreement with that by the microsolvability theory.

关 键 词：相场法 耦合强度 微观可解理论 二次枝晶 

分 类 号：TG111[金属学及工艺—物理冶金]