采用Al-4%Cu合金, 对不同抽拉速率下定向凝固枝晶界面特征进行了研究. 结果表明, 当抽拉速率从100 um/s增至600 um/s时, 一次枝晶间距随抽拉速率的增大而减小. 在枝晶固/液 界面存在枝晶干的凸起, 其平--凸--平--凸的程度随抽拉速率的增加呈现先加强后减弱最后几乎消 失的规律. 随着抽拉速率的增大, 枝晶尖端温度先升高而后降低. 采用KGT模型和非平衡效应 研究了枝晶界面温度, 分析了尖端过冷度和尖端成分对枝晶界面特征的影响, 得到非平衡凝固枝 晶尖端过冷度的计算方程. 界面平-凸-平-凸的程度与枝晶尖端成分和尖端过冷度有关.
Directional solidification experiments were carried out on Al-4wt%Cu alloy under different withdrawal velocities. It is showed that the primary dendrite arm spacing decreases with increasing withdrawal velocity which is rapid. The solid/liquid interface of dendrite is planar-convex-planar-convex, and it is reinforced first and then weakened and finally almost faded. Dendrite tip temperature is also first increased and then decreased with increasing withdrawal velocity. The KGT model and non-equilibrium effect were used to research the dendrite tip temperature, tip undercooling and composition. This explains the change of dendrite interface morphology well.
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