Molecular-dynamics method for the simulation of grain-boundary migration
Molecular-dynamics method for the simulation of grain-boundary migration
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DOI：
10.1023/a:1008663804495
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发表时间：
1997-11-01
期刊：
影响因子：
--
通讯作者：
Furtkamp, M
中科院分区：
文献类型：
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作者：
Schonfelder, B;Wolf, D;Furtkamp, M
介绍并验证了一种用于模拟单个平坦晶界的固有迁移行为的分子动力学方法。通过在双晶上施加各向异性弹性应变，使其两半的弹性能量密度不同，产生晶界迁移的恒定驱动力。对于 Cu 中大平面晶胞、高角度 (001) 扭曲边界的模型情况，我们表明，大约 1%-4% 的弹性应变足以在远低于熔点的温度下驱动边界的连续粘性运动。由此产生的驱动力（在实验可达到的范围的高端）使得能够在通常通过分子动力学模拟可达到的10(-9) s的时间范围内对迁移过程进行定量评估。对于这个模型的高角度晶界，我们证明了（a）漂移速度确实与所施加的驱动力成正比，从而使我们能够确定边界迁移率，（b）晶界迁移的激活能明显低于晶界自扩散甚至熔体中自扩散的激活能，（c）与早期的模拟一致，迁移机制涉及小原子团局部无序（“熔化”）期间的集体重新洗牌以及随后的重新凝固。另一个水晶。
A molecular-dynamics method for the simulation of the intrinsic migration behavior of individual, flat grain boundaries is introduced and validated. A constant driving force for grain-boundary migration is generated by imposing an anisotropic elastic strain on a bicrystal such that the elastic-energy densities in its two halves are different. For the model case of a large-planar-unit-cell, high-angle (001) twist boundary in Cu we show that an elastic strain of similar to 1%-4% is sufficient to drive the continuous, viscous movement of the boundary at temperatures well below the melting point. The driving forces thus generated (at the high end of the experimentally accessible range) enable a quantitative evaluation of the migration process during the time frame of 10(-9) s typically accessible by molecular-dynamics simulation. For this model high-angle grain boundary we demonstrate that (a) the drift velocity is, indeed, proportional to the applied driving force thus enabling us to determine the boundary mobility, (b) the activation energy for grain-boundary migration is distinctly lower than that for grain-boundary self-diffusion or even self-diffusion in the melt and (c) in agreement with earlier simulations the migration mechanism involves the collective reshuffling during local disordering (''melting'') of small groups of atoms and subsequent resolidification onto the other crystal.