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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 Karma-based thin-field limit-phase field model, the effect of coupling strength between phase field and temperature field on the dendrite growth behavior in undercooled pure Ni melt was studied. The simulation results show that with the decrease of the thermal coupling strength, the phase field is weakened by the influence of the temperature field, the disturbance at the front of the solid-liquid interface becomes larger, the main dendrites appear secondary dendrite and gradually developed and roughened, and the roughening mode Friction cut to the dendrite arm merge mode change. At the same time, the growth rate of dendritic tip increases and the radius of curvature decreases. The dendritic tip growth rate is larger than the steady state growth rate in the transient process. As the growth progresses, the dendritic tip growth rate gradually decreases until the steady state value is reached. The calculated results are in good agreement with the microscopic solvable theory.