A macro-scale ruck and tuck mechanism for deformation in ion-irradiated polycrystalline graphite
A macro-scale ruck and tuck mechanism for deformation in ion-irradiated polycrystalline graphite
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DOI：
10.1016/j.carbon.2020.10.086
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发表时间：
2021-03
期刊：
影响因子：
10.9
通讯作者：
Dong Liu;D. Cherns;S. Johns;Yan Zhou;Junliang Liu;Wei-Ying Chen;I. Griffiths;C. Karthik;Meimei Li;M. Kuball;Joshua J. Kane;W. Windes
中科院分区：
文献类型：
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作者：
Dong Liu;D. Cherns;S. Johns;Yan Zhou;Junliang Liu;Wei-Ying Chen;I. Griffiths;C. Karthik;Meimei Li;M. Kuball;Joshua J. Kane;W. Windes
在多晶高定向热解石墨(HOPG)表面，用离子注入方式(高达1.8×10~(17)ion/cm~2)和Ar~+离子注入后，在表面形成了明显的纹状结构。研究发现，这些纹理与晶体取向无关，并与气孔的形成有关。在静脉的下面，形成了一个三角形的核心，核心内的石墨板向上移动到表面。因此，在这些三角形构造边界处产生了宏观尺度的‘ruck&tuck’几何图形。在辐照过程中观察到位错沿基面的渐进运动，并在此基础上提出了一个解释血管形成的力学模型。辐照后，多晶石墨的FC间距略有增加，但宏观纹路的形成在多晶石墨的尺寸和性能变化中起着更为重要的作用，特别是在存在应力梯度的情况下。该模型还解释了高能石油气的热膨胀随辐照的变化。与Heggie的“ruck&tuck”模型和巴苏姆的“涟漪定位”模型一起，本模型被认为为石墨材料中的辐照行为提供了另一种经过实验验证的机制。
A vein structure, which becomes more pronounced with increasing ion dose, was found on the surface of polycrystalline HOPG (highly oriented pyrolytic graphite) implanted byex situC+(up to 1.8 × 1017ions/cm2), andin situAr+in a transmission electron microscope (TEM). These veins are found to be independent of the crystallographic orientations and are associated with the formation of pores. Underneath the veins, a triangular-shaped core was formed with the graphite platelet inside the core displaced up towards the surface. A macro-scale ‘ruck&tuck’ geometry was thus generated at these triangle structure boundaries. Progressive movement of dislocations along basal planes during irradiation was observed, and a mechanistic model was proposed on this basis to explain the vein formation. A small increase ofc-spacing was observed with irradiation but it is believed that macro-scale vein formation plays a more vital role in the dimensional and property changes in polycrystalline graphite, especially when a stress gradient is present. The model proposed also explains the change of thermal expansion in HOPG with irradiation. Together with Heggie’s ‘ruck&tuck’ and Barsoum’s ‘ripplocations’ models, the present model is considered to have provided an additional experimentally proven mechanism responsible for irradiation behaviour in graphite materials.