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首页> 外文期刊>Journal of Alloys and Compounds: An Interdisciplinary Journal of Materials Science and Solid-state Chemistry and Physics >Molecular dynamics study on microstructural evolution during crystallization of rapidly supercooled zirconium melts
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Molecular dynamics study on microstructural evolution during crystallization of rapidly supercooled zirconium melts

机译：快速过冷锆熔体结晶过程中微观结构演变的分子动力学研究

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Molecular dynamics simulations have been performed to explore the crystallization mechanism under rapid cooling for Zirconium that has body-centred cubic (bcc) and hexagonal close-packed (hcp) phases separated at 1136 K. The structural evolution was analysed in terms of the system energy, the pair (and angular) distribution function, and the largest standard cluster analysis. It is found that the critical cooling rate (gamma(c)) for vitrification is about 5.0 x 10(13) K/s, and the Ostwald's step rule is applied to Zr. Crystallization always takes the pathway of supercooled-liquid (scl) -> bcc -> hcp, determined by the competition between thermodynamics and kinetics at different conditions. Particularly with gamma decrease both the onset temperature of scl -> bcc and the maximal number of bcc atoms increase gamma while both the onset temperature of the bcc -> hcp transition and the rate of different crystalline atoms in the final solids are randomly. A rather perfect bcc phase can be obtained at gamma < 1.0 x 10(12) K/s, however, it is unstable and always transforms to the stable hcp phase under all conditions examined here. In the final solids, most of face-centred cubic (fcc) structures act as the hcp crystalline boundaries not comprises individual fcc phase. These findings are useful for understanding the crystallization of metals, especially for those that have a high-temperature-stabled phase. (C) 2016 Elsevier B.V. All rights reserved.
机译：已经进行了分子动力学模拟以探索快速冷却的锆的结晶机理，该锆的体心立方（bcc）相和六方紧密堆积（hcp）相在1136 K下分离。从系统能量的角度分析了结构演化，线对（和角度）分布函数以及最大的标准聚类分析。发现用于玻璃化的临界冷却速率（gamma（c））约为5.0 x 10（13）K / s，并且Ostwald的阶跃规则适用于Zr。结晶总是采用过冷液体（scl）-> bcc-> hcp的途径，这取决于不同条件下热力学和动力学之间的竞争。特别是随着γ的降低，scl-> bcc的起始温度和最大bcc原子数都会增加γ，而bcc-> hcp转变的起始温度和最终固体中不同晶体原子的比率都是随机的。在γ<1.0 x 10（12）K / s的情况下可以获得相当理想的bcc相，但是，它是不稳定的，并且在此处检查的所有条件下都始终转换为稳定的hcp相。在最终固体中，大多数面心立方（fcc）结构充当hcp晶界，但不包含单个fcc相。这些发现有助于理解金属的结晶，特别是对于那些具有高温稳定相的金属。 （C）2016 Elsevier B.V.保留所有权利。

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