Stress-enhanced grain growth in a nanocrystalline material by molecular-dynamics simulation
Stress-enhanced grain growth in a nanocrystalline material by molecular-dynamics simulation
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DOI：
10.1016/s1359-6454(03)00011-9
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发表时间：
2003-04-18
期刊：
影响因子：
9.4
通讯作者：
Gleiter, H
中科院分区：
文献类型：
--
作者：
Haslam, AJ;Moldovan, D;Gleiter, H
分子动力学模拟用于阐明晶粒生长和晶界扩散蠕变之间的耦合在一个多晶组成的25个晶粒的平均晶粒尺寸约为15 nm和柱状晶粒形状。与我们先前模拟的晶界扩散蠕变相一致，尽管在没有晶粒生长的情况下，我们发现，最初，即在显著的晶粒生长开始之前，变形通过Coble蠕变机制进行。此外，与我们早期的晶粒生长模拟在没有应力的情况下，观察到两种生长机制在变形：生长由于曲率驱动的GB迁移和生长导致的晶粒旋转引起的晶粒聚结。在所施加的应力的存在下观察到的晶粒生长的比较，仅响应于温度作为驱动力，使我们能够识别的机制，外部应力影响晶粒生长。特别是，我们发现，GB迁移和晶粒旋转加速的变形。(C)2003由Elsevier Science Ltd代表Acta Materialia Inc.出版。
Molecular-dynamics simulations are used to elucidate the coupling between grain growth and grain-boundary diffusion creep in a polycrystal consisting of 25 grains with an average grain size of about 15 nm and a columnar grain shape. Consistent with our earlier simulations of grain-boundary diffusion creep, albeit in the absence of grain growth, we find that initially, i.e. prior to the onset of significant grain growth, the deformation proceeds via the mechanism of Coble creep. Also, consistent with our earlier grain-growth simulations in the absence of stress, two growth mechanisms are observed during the deformation: growth due to curvature-driven GB migration and growth resulting from grain rotation-induced grain coalescence. The comparison of the grain growth observed in the presence of the applied stress with that solely in response to temperature as the driving force enables us to identify the mechanisms by which external stress affects grain growth. In particular, we find that both GB migration and grain rotation are accelerated by the deformation. (C) 2003 Published by Elsevier Science Ltd on behalf of Acta Materialia Inc.