Subsurface structural change of silica upon nanoscale physical contact: Chemical plasticity beyond topographic elasticity
Subsurface structural change of silica upon nanoscale physical contact: Chemical plasticity beyond topographic elasticity
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DOI：
10.1016/j.actamat.2021.116694
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发表时间：
2021-04
期刊：
影响因子：
9.4
通讯作者：
Hongtu He;Zhe Chen;Yen‐Ting Lin;S. Hahn;Jiaxin Yu;A. V. van Duin;T. Gokus;S. Rotkin;Seong H. Kim
中科院分区：
文献类型：
--
作者：
Hongtu He;Zhe Chen;Yen‐Ting Lin;S. Hahn;Jiaxin Yu;A. V. van Duin;T. Gokus;S. Rotkin;Seong H. Kim
材料表面的缺陷或与异物物理接触造成的缺陷会恶化其机械性能，并限制技术应用。因此，了解接触引起的亚表面损伤具有重要意义。利用纳米级红外光谱和反应分子动力学模拟技术，研究了二氧化硅在纳米压痕和纳米刻蚀过程中亚表面结构的变化。结果表明，即使在地形弹性接触之后，Sisingle Bondo键长分布也是伸长的，这表明在亚埃水平上存在“化学塑性”。在具有亚表面致密化的塑性区，Sisingle Bondo键比原始区域略长，表明摩尔体积的减少伴随着Sisingle Bondo键的伸长，而不是缩短。这些结果说明，材料在物理接触时的结构损伤不能基于表面的地形变形来描述。
Surface defects or flaws on materials made by physical contacts with foreign objects can deteriorate their mechanical properties and limit technical applications. Thus, understanding the contact-induced subsurface damage is of great importance. Using nanoscale infrared spectroscopy and reactive molecular dynamics simulations, the subsurface structural changes of silica upon nanoindentation and nanoscratch are investigated. The results reveal an elongation of the Sisingle bondO bond length distribution even after the topographically-elastic contact, indicating a “chemical plasticity” at the sub-Angstrom level. In the plastic region with subsurface densification, the Sisingle bondO bond is found to be slightly longer than the pristine region, indicating the decrease in molar volume is accompanied with the elongation, not shortening, of the Sisingle bondO bond. These results elucidate the structural damage of a material upon physical contact cannot be delineated based on the topographic deformation of the surface.