Deformation behaviour of [001] oriented MgO using combined in-situ nano-indentation and micro-Laue diffraction
Deformation behaviour of [001] oriented MgO using combined in-situ nano-indentation and micro-Laue diffraction
复制标题
DOI：
10.1016/j.actamat.2017.12.002
复制
发表时间：
2018-02-15
期刊：
影响因子：
9.4
通讯作者：
Giuliani, Finn
中科院分区：
文献类型：
--
作者：
Bhowmik, Ayan;Lee, Junyi;Giuliani, Finn
本文报道了一个具有空间和时间分辨率的耦合原位微劳厄衍射和纳米压痕实验，以研究[001]取向单晶MgO的变形机制。晶体塑性有限元建模，以帮助解释塑性的实验观察。劳厄点在压痕时显示出旋转和条纹，这通常分别指示材料中的弹性晶格旋转和塑性应变梯度。劳厄峰的条纹的多个面表明塑性滑移发生在几乎所有的{101}型滑移面上，所述滑移面与样品表面成45度，而在90度{110}面上没有滑移的迹象。晶体塑性模型也支持这些实验观察。由于压头下的非对称滑动，如通过建模结果预测和通过劳厄分析观察到的，亚晶粒被发现成核具有明显的取向差。随着循环加载，MgO的机械滞后行为是通过劳厄反射的变化的配置文件，驱动由存储的弹性能量的塑性应变的逆转揭示。晶体塑性模拟也明确表明，在随后的加载循环后，第一次，二次滑移系统完全弹性卸载，而一些塑性应变的主滑移逆转。追踪劳厄峰的移动，可以看到在下的材料中发生了更高程度的晶格旋转，其在横向远离时逐渐减小。随着变形的进行，我们还构造了全场弹性应变和转动梯度，它们显示出在应变片两侧相反的晶格转动。(C)2017 Acta Materialia Inc.爱思唯尔有限公司出版
We report a coupled in-situ micro-Laue diffraction and nano-indentation experiment, with spatial and time resolution, to investigate the deformation mechanisms in [001]-oriented single crystal MgO. Crystal plasticity finite element modelling was applied to aid interpretation of the experimental observations of plasticity. The Laue spots showed both rotation and streaking upon indentation that is typically indicative of both elastic lattice rotation and plastic strain gradients respectively in the material. Multiple facets of streaking of the Laue peaks suggested plastic slip occurring on almost all the {101}-type slip planes oriented 45 degrees to the sample surface with no indication of slip on the 90 degrees {110}-planes. Crystal plasticity modelling also supported these experimental observations. Owing to asymmetric slip beneath the indenter, as predicted by modelling results and observed through Laue analysis, sub-grains were found to nucleate with distinct misorientation. With cyclic loading, the mechanical hysteresis behaviour in MgO is revealed through the changing profiles of the Laue reflections, driven by reversal of plastic strain by the stored elastic energy. Crystal plasticity simulations have also shown explicitly that in subsequent loading cycles after first, the secondary slip system unloads completely elastically while some plastic strain of the primary slip reverses. Tracking the Laue peak movement, a higher degree of lattice rotation was seen to occur in the material under the indent, which gradually decreased moving laterally away. With the progress of deformation, the full field elastic strain and rotation gradients were also constructed which showed opposite lattice rotations on either sides of the indent. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd.