Dynamic microstructural evolution of graphite under displacing irradiation
Dynamic microstructural evolution of graphite under displacing irradiation
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DOI：
10.1016/j.carbon.2013.11.002
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发表时间：
2014-03-01
期刊：
影响因子：
10.9
通讯作者：
Donnelly, S. E.
中科院分区：
文献类型：
--
作者：
Hinks, J. A.;Haigh, S. J.;Donnelly, S. E.
石墨材料和石墨复合材料暴露于辐射诱导的原子位移时经历尺寸变化。这对当前和未来的技术具有重大意义，从核裂变反应堆到石墨烯-硅混合器件的加工。在核石墨的尺寸变化是一个复杂的问题，涉及到填料，粘合剂，孔隙率，裂纹和原子级的影响，所有的多颗粒结构内的相互作用。一个更好的理解驱动单个石墨晶体内的尺寸变化的原子机制，需要到这个系统的多尺度modeling，在这项研究中，micromechanically剥离样品的高度定向热解石墨已被离子辐照和原位研究，使用透射电子显微镜（TEM），以获得洞察到单个石墨晶体的位移辐射的响应。在连续的离子轰击下，一个复杂的动态序列的变形演变具有几个不同的阶段，从诱导的应变，产生位错导致位错阵列，形成扭结带网络和局部隆起的样品。使用原位TEM观察这些离子辐照诱导的过程，揭示了驱动这些现象的微观结构发展和物理学序列的先前未知的细节。与观察到的微观结构的变化一致的机理模型。(C)2013爱思唯尔有限公司版权所有。
Graphitic materials and graphite composites experience dimensional change when exposed to radiation-induced atomic displacements. This has major implications for current and future technological ranging from nuclear fission reactors to the processing of graphene-silicon hybrid devices. Dimensional change in nuclear graphites is a complex problem involving the filler, binder, porosity, cracks and atomic-level effects all interacting within the polygranular structure. An improved understanding of the atomistic mechanisms which drive dimensional change within individual graphitic crystals is required to feed into the multiscale modelling of this system.In this study, micromechanically exfoliated samples of highly oriented pyrolytic graphite have been ion irradiated and studied in situ using transmission electron microscopy (TEM) in order to gain insights into the response of single graphitic crystals to displacing radiation. Under continuous ion bombardment, a complex dynamic sequence of deformation evolves featuring several distinct stages from the inducement of strain, the creation of dislocations leading to dislocation arrays, the formation of kink band networks and localised doming of the sample. Observing these ion irradiation-induced processes using in situ TEM reveals previously unknown details of the sequence of microstructural developments and physics driving these phenomena. A mechanistic model consistent with the microstructural changes observed is presented. (C) 2013 Elsevier Ltd. All rights reserved.