Effect of local structures on structural evolution during crystallization in undercooled metallic glass-forming liquids.
Effect of local structures on structural evolution during crystallization in undercooled metallic glass-forming liquids.
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DOI：
10.1063/1.4792067
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发表时间：
2013-02
期刊：
影响因子：
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通讯作者：
Z. W. Wu;M. Li;Wen-Qiong Wang;W. Song;K. Liu
中科院分区：
文献类型：
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作者：
Z. W. Wu;M. Li;Wen-Qiong Wang;W. Song;K. Liu
通过分子动力学模拟研究了过冷ZrCu金属玻璃形成液结晶过程中局部结构对结构演化的影响。研究发现，体心立方（bcc）类团簇在结晶过程中的结构演化中发挥着关键作用。与之前的推测相反，类 bcc 晶核的数量在结晶开始之前并没有太大变化。相反，在退火过程中类似 bcc 的临界核的发展导致与其周围其他核具有很强的空间相关性，形成晶体结构模板。研究还发现，类面心立方核的尺寸分布在退火早期遵循指数截止的幂律形式，但在结晶开始前转变为纯幂律行为。这意味着晶体结构模板具有分形特征，并且过冷液体在结晶开始之前演化到自组织临界状态，这可能引发随后的快速结晶。根据图论分析，还发现不同液体样品中观察到的结晶起始时间的大分散性是由类bcc簇的连通性造成的。
The effect of local structures on structural evolution during the crystallization of undercooled ZrCu metallic glass-forming liquid was studied via molecular dynamics simulations. It is found that body-centered-cubic (bcc)-like clusters play a key role in structural evolution during crystallization. In contrast to previous speculations, the number of bcc-like crystal nuclei does not change much before the onset of crystallization. Instead, the development of a bcc-like critical nucleus during annealing leads to a strong spatial correlation with other nuclei in its surroundings, forming a crystalline structure template. It is also found that the size distribution of bcc-like nuclei follows a power-law form with an exponential cutoff in the early stage of annealing, but changes to a pure power-law behavior just before the onset of crystallization. This implies that the crystalline structure template has fractal feature and the undercooled liquids evolve to a self-organized critical state before the onset of crystallization, which might trigger the subsequent rapid crystallization. According to the graph theory analysis, it is also found that the observed large scatter of the onset time of crystallization in different liquid samples results from the connectivity of the bcc-like clusters.