Crystal-melt interfacial free energies in hcp metals: A molecular dynamics study of Mg
Crystal-melt interfacial free energies in hcp metals: A molecular dynamics study of Mg
复制标题
hcp 金属中的晶体熔体界面自由能：镁的分子动力学研究
DOI：
10.1103/physrevb.73.024116
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发表时间：
2006-01-01
影响因子：
3.7
通讯作者：
Srolovitz, DJ
中科院分区：
文献类型：
--
作者：
Sun, DY;Mendelev, MI;Srolovitz, DJ
采用平衡分子动力学(MD)模拟和毛细管涨落方法(CFM)计算了HCP镁的晶体-熔体界面自由能。这项工作利用了一种新开发的嵌入原子方法(EAM)，使镁的原子间相互作用势符合晶体、液体和熔化性质。我们描述了以前只应用于立方系的CFM如何被推广到研究六方金属，方法是对六角谐函数的取向度与数学的关系进行了参数化。用该方法计算了晶体的特恩布尔系数和晶体各向异性。结果表明，不同高对称性取向的界面自由能相差约1%，得到的数值为{α}=0.48$。这些结果与以前对立方EAM金属的MD-CFM研究以及对HCP合金固-液界面的实验研究结果进行了比较。此外，还讨论了我们的结果对预测HCP金属中枝晶生长方向的意义。
Crystal-melt interfacial free energies $(\ensuremath{\gamma})$ are computed for hcp Mg by employing equilibrium molecular-dynamics (MD) simulations and the capillary-fluctuation method (CFM). This work makes use of a newly developed embedded-atom-method (EAM) interatomic potential for Mg fit to crystal, liquid, and melting properties. We describe how the CFM, which has previously been applied to cubic systems only, can be generalized for studies of hcp metals by employing a parametrization for the orientation dependence of $\ensuremath{\gamma}$ in terms of hexagonal harmonics. The method is applied in the calculation of the Turnbull coefficient $(\ensuremath{\alpha})$ and crystalline anisotropies of $\ensuremath{\gamma}$. We obtain a value of $\ensuremath{\alpha}=0.48$, with interfacial free energies for different high-symmetry orientations differing by approximately 1%. These results are compared to those obtained in previous MD-CFM studies for cubic EAM metals as well as experimental studies of solid-liquid interfaces in hcp alloys. In addition, the implications of our results for the prediction of dendrite growth directions in hcp metals are discussed.