The anisotropy of hexagonal close-packed and liquid interface free energy using molecular dynamics simulations based on modified embedded-atom method
The anisotropy of hexagonal close-packed and liquid interface free energy using molecular dynamics simulations based on modified embedded-atom method
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DOI：
10.1016/j.actamat.2016.01.043
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发表时间：
2016-04
期刊：
影响因子：
9.4
通讯作者：
E. Asadi;M. A. Zaeem
中科院分区：
文献类型：
--
作者：
E. Asadi;M. A. Zaeem
采用基于改进嵌入原子方法的分子动力学模拟方法，对密排六方晶系（HCP）-液体界面自由能的各向异性进行了全面的研究。作为案例研究，所有的模拟都是针对镁（Mg）进行的。采用固-液共存的方法精确计算了熔点和熔融性质。然后，采用毛细涨落法（CFM）确定HCP-液体界面自由能（γ）和各向异性参数。在CFM中，连续序参量被用来精确定位HCP-液体界面位置，并且HCP自适应球谐函数被用来根据其各向异性参数（ε 20、ε 40、ε 60和ε 66）展开γ。八个滑移和孪生平面（基底，两个棱柱，两个金字塔，和三个孪生平面）被认为是HCP-液体界面平面。预测了HCP-液体界面平均自由能为122.2（mJ/m2），ε 20、ε 40和ε 66参数不为零，Mg的ε 60参数近似为零。利用这些结果，预测了Mg凝固过程中的第一优先枝晶生长方向为[11 2 <$0]，这与实验结果一致。此外，Mg的第二优选枝晶生长方向被预测为[33 6 <$2]。
This work aims to comprehensively study the anisotropy of the hexagonal close-packed (HCP)-liquid interface free energy using molecular dynamics (MD) simulations based on the modified-embedded atom method (MEAM). As a case study, all the simulations are performed for Magnesium (Mg). The solid–liquid coexisting approach is used to accurately calculate the melting point and melting properties. Then, the capillary fluctuation method (CFM) is used to determine the HCP-liquid interface free energy (γ) and anisotropy parameters. In CFM, a continuous order parameter is employed to accurately locate the HCP-liquid interface location, and the HCP symmetry-adapted spherical harmonics are used to expand γ in terms of its anisotropy parameters (ε 20, ε 40, ε 60 and ε 66). Eight slip and twinning planes (basal, two prismatic, two pyramidal, and three twinning planes) are considered as the HCP-liquid interface planes. An average HCP-liquid interface free energy of 122.2 (mJ/m 2), non-zero ε 20, ε 40, and ε 66 parameters, and approximately zero ε 60 parameter for Mg are predicted. Using these findings, the first preferred dendrite growth direction in solidification of Mg is predicted as [11 2¯ 0], which is in agreement with experiments. Also, a second preferred dendrite growth direction for Mg is predicted as [33 6¯ 2].