Diffusion-controlled crystal growth in deeply undercooled melt on approaching the glass transition
Diffusion-controlled crystal growth in deeply undercooled melt on approaching the glass transition
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DOI：
10.1103/physrevb.83.014202
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发表时间：
2011-01
影响因子：
3.7
通讯作者：
Q. Wang;Li-Min Wang;M. Ma;S. Binder;T. Volkmann;D. Herlach;J. Wang;Q. Xue;Yongjun Tian;Riping Liu
中科院分区：
文献类型：
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作者：
Q. Wang;Li-Min Wang;M. Ma;S. Binder;T. Volkmann;D. Herlach;J. Wang;Q. Xue;Yongjun Tian;Riping Liu
其它文献报道过冷时金属熔体的晶体生长速度单调增加。然而，传统的增长理论并没有预测到这种现象。在这项工作中，通过测量Zr50Cu50金属熔体在325 K的过冷范围内的生长速度来解决这个问题。在过冷200k时观察到最大生长速度，而不是文献中报道的单调增长。我们发现平面生长理论或枝晶生长理论都可以解释最大生长速度的数值，但预测的最大生长速度在过冷时的位置远远小于实验结果。在现有结果的帮助下，建立了各种物质熔体晶体生长的一般模式，其中所有缓慢的晶体生长动力学都可以用深度过冷时的扩散控制机制来解释。
Crystal-growth velocity in metallic melts has been reported by others to increase monotonically with undercooling. Nevertheless, such an observation is not predicted by conventional growth theory. In this work, the metallic melt of Zr50Cu50 is studied to address the problem by measuring the growth velocity over a wide range of undercooling up to 325 K. A maximum growth velocity is observed at an undercooling of 200 K instead of the monotonic increase reported in the literature. We find that the planar or dendrite growth theories can explain the value of the maximum growth velocity, but the predicted location of the maximum in undercooling is far less than that seen by experiment. With the assistance of current results, a general pattern of crystal growth is established for melts of a variety of substances, where all sluggish crystal-growth kinetics is explained by the diffusion-controlled mechanism at deep undercooling.