Zhang Xin, Lu Wenliang, Liang Zun, Wang Yashen, Lv Songtai, Liang Hongtao, Laird Brian B, Yang Yang
State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China.
School of Science, Changzhou Institute of Technology, Changzhou, Jiangsu 213032, China.
J Chem Phys. 2022 Aug 28;157(8):084709. doi: 10.1063/5.0101348.
We present a classical molecular-dynamics study of the collective dynamical properties of the coexisting liquid phase at equilibrium body-centered cubic (BCC) Fe crystal-melt interfaces. For the three interfacial orientations (100), (110), and (111), the collective dynamics are characterized through the calculation of the intermediate scattering functions, dynamical structure factors, and density relaxation times in a sequential local region of interest. An anisotropic speedup of the collective dynamics in all three BCC crystal-melt interfacial orientations is observed. This trend differs significantly from the previously observed slowing down of the local collective dynamics at the liquid-vapor interface [del Rio and González, Acta Mater. 198, 281 (2020)]. Examining the interfacial density relaxation times, we revisit the validity of the recently developed time-dependent Ginzburg-Landau theory for the solidification crystal-melt interface kinetic coefficients, resulting in excellent agreement with both the magnitude and the kinetic anisotropy of the crystal-melt interface kinetic coefficients measured from the non-equilibrium molecular-dynamics simulations.
我们展示了一项关于平衡体心立方（BCC）铁晶体 - 熔体界面处共存液相集体动力学性质的经典分子动力学研究。对于（100）、（110）和（111）这三种界面取向，通过在连续的局部感兴趣区域计算中间散射函数、动态结构因子和密度弛豫时间来表征集体动力学。在所有三种BCC晶体 - 熔体界面取向中均观察到集体动力学的各向异性加速。这种趋势与之前在液 - 气界面观察到的局部集体动力学减慢[德尔·里奥和冈萨雷斯，《材料学报》198, 281 (2020)]有显著差异。通过研究界面密度弛豫时间，我们重新审视了最近发展的用于凝固晶体 - 熔体界面动力学系数的含时金兹堡 - 朗道理论的有效性，结果与从非平衡分子动力学模拟测量得到的晶体 - 熔体界面动力学系数的大小和动力学各向异性都非常吻合。
