采用透明合金SCN-1.48wt%Salol进行恒速定向凝固实验，考察了一次间距、尖端半径和尖端温度随凝固生长速度变化的规律。通过考察平界面失稳孕育时间和失稳时界面速度的关系获得了平界面失稳的临界速度，从而准确确定了合金成分。实验发现，随着生长速度的增大，一次间距先减小到一个极小值然后又增大一个极大值，随后逐渐下降，呈现S形的变化趋势，并且在从极小值增大到极大值区间发生了胞／枝转变。将实验结果与经典的BH-L模型以及自洽数值模型进行了比较，发现BH-L模型所预言的尖端温度与实验结果存在较大偏差，而所有实验结果与自洽模型得到了较好的吻合。
A transparent model alloy, succininitrile-1.48 wt%Salol, was directionally solidified on a temperature gradient stage at the constant velocity. The primary spacing, tip radius and tip temperatures have been measured as a function of growth rate. The critical velocity for planar interface instability Vc was obtained. It is shown that, with the increase of growth velocity, the primary spacing decreases first, go through a local minimum value, and then increases to a local maximum value, finally decrease again. The cell-dendrite transition happens when the primary spacing increases from the local minimum to maximum value. Experimental results were compared to BH-L and self-consistent model. It’s found that the tip temperature predicted by BH-L model shows a large difference with the experimental results, and there shows a good agreement between all experimental results and self-consistent model.
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