Dremov Vladimir V, Chirkov Pavel V, Karavaev Alexey V
Federal State Unitary Enterprise "Russian Federal Nuclear Center-Zababakhin All-Russia Research Institute of Technical Physics", 13 Vasiliev st., Snezhinsk, Chelyabinsk Region, 456770, Russia.
Sci Rep. 2021 Jan 13;11(1):934. doi: 10.1038/s41598-020-79861-3.
The paper presents results of a large-scale classical molecular dynamics study into the effect of ingrain defects on the grain growth rate of face centered cubic nanocrystalline material under thermal annealing. To do this, two types of virtual MD samples are used. The samples of the first type are constructed artificially by filling Voronoi cells with atoms arranged in fcc lattice essentially with no ingrain defects. The other samples are obtained by natural crystallization from melted material and contain numerous extended ingrain defects. These samples with a high concentration of ingrain defects imitate nanocrystalline material produced by severe plastic deformation via high pressure torsion or equal channel angular extrusion. The samples of both types are subjected to long-time zero pressure isothermal annealing at [Formula: see text] ([Formula: see text] is melting temperature) which leads to grain coarsening due to recrystallization. Direct molecular dynamics simulations of the annealing of different samples show that at the same conditions recrystallization goes two times faster in the samples with a high concentration of extended ingrain defects than in the defect-free samples. That is, to increase the thermal stability of nanostructured material the technologies used for forming nanocrystalline structures should be developed so as to avoid the thermomechanical treatment regimes leading to the formation of structures with high concentration of ingrain defects.
本文展示了一项大规模经典分子动力学研究的结果，该研究探讨了内禀缺陷对面心立方纳米晶材料在热退火过程中晶粒生长速率的影响。为此，使用了两种类型的虚拟分子动力学样本。第一类样本是通过用基本无内禀缺陷的面心立方晶格原子填充Voronoi胞人工构建的。另一类样本是通过熔化材料自然结晶获得的，含有大量扩展的内禀缺陷。这些具有高浓度内禀缺陷的样本模拟了通过高压扭转或等通道角挤压严重塑性变形产生的纳米晶材料。两类样本都在[公式：见原文]（[公式：见原文]为熔化温度）下进行长时间零压力等温退火，这会由于再结晶导致晶粒粗化。对不同样本退火的直接分子动力学模拟表明，在相同条件下，具有高浓度扩展内禀缺陷的样本中的再结晶速度比无缺陷样本快两倍。也就是说，为了提高纳米结构材料的热稳定性，应开发用于形成纳米晶结构的技术，以避免导致形成具有高浓度内禀缺陷结构的热机械处理方式。
