The Effect of Grain Boundaries on Plastic Deformation of Olivine
The Effect of Grain Boundaries on Plastic Deformation of Olivine
复制标题
晶界对橄榄石塑性变形的影响
DOI：
10.1029/2020jb020273
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发表时间：
2021-07-01
影响因子：
3.9
通讯作者：
Marquardt, Katharina
中科院分区：
文献类型：
--
作者：
Ferreira, Filippe;Hansen, Lars N.;Marquardt, Katharina
橄榄石的塑性变形已经被研究了几十年。然而，在变形过程中，例如在位错适应的晶界滑动状态中，晶界的精确作用仍然知之甚少。具体来说，我们缺乏关于变形过程中晶界与其他缺陷（例如位错）相互作用的方式的知识。为了研究位错和晶界的相互作用，我们分析了扭转变形的 Fo(50) 多晶聚集体中晶界的结构和分布（Hansen、Zimmerman、Dillman 和 Kohlstedt，2012，）。我们使用电子背散射衍射和透射电子显微镜在三个垂直方向上表征了聚集体的微观结构。塑性应变的增加与强晶体择优取向和晶界平面分布的发展相关，晶界平面分布从均匀分布演变为以（010）型平面为主的分布。我们使用 m' 因子，根据相邻晶粒之间滑移系统的相对方向来评估位错跨晶界传输的潜力。随着变形的进行，我们的分析表明明显滑移透明边界的数量不断增加，直到达到中等应变（gamma = 4）。基于这些观察，我们提出特定类型的晶界是由位错活动产生的，并且位错输入晶界促进了晶界滑动。我们的研究结果提供了对橄榄石变形微观物理的深入了解，并强调了岩石变形过程中粒间和粒内机制耦合研究的重要性。
The plastic deformation of olivine has been studied for decades. However, the precise role of grain boundaries during deformation in, for example, the dislocation-accommodated grain-boundary sliding regime, remains poorly understood. Specifically, we lack knowledge regarding the manner in which grain boundaries interact with other defects, such as dislocations, during deformation. To investigate the interaction of dislocations and grain boundaries, we analyzed the structure and distribution of grain boundaries in a polycrystalline aggregate of Fo(50) deformed in torsion (Hansen, Zimmerman, Dillman, & Kohlstedt, 2012, ). We characterized the microstructure of the aggregate using electron-backscatter diffraction and transmission electron microscopy in three perpendicular directions. An increase in plastic strain is associated with the development of a strong crystallographic preferred orientation and a grain-boundary plane distribution that evolves from a uniform distribution to one dominated by (010)-type planes. We use the m' factor, to evaluate the potential for transmission of dislocations across grain boundaries based on the relative orientations of slip systems between neighboring grains. With progressive deformation, our analysis indicates an increase in abundance of apparently slip-transparent boundaries until moderate strains (gamma = 4) are reached. Based on these observations, we propose that specific types of grain boundaries are created by dislocation activity and that the input of dislocations into grain boundaries facilitates grain-boundary sliding. Our results provide insight into the microphysics of olivine deformation and highlight the importance of the coupled study of inter- and intragranular mechanisms during rock deformation.