Zhu Xiaolin, Li Jijun, Zhang Lihua, Lang Fengchao, Hou Xiaohu, Zhao Xueping, Zhang Weiguang, Zhao Chunwang, Yang Zijian
College of Science, Inner Mongolia University of Technology, Hohhot 010051, China.
School of Mechanical and Energy Engineering, Shanghai Technical Institute of Electronics & Information, Shanghai 201411, China.
Micromachines (Basel). 2023 Feb 8;14(2):404. doi: 10.3390/mi14020404.
In this study, nanoindentation tests at three different strain rates within 100 nm indentation depth were conducted on an a-plane (112¯0) ZnO single crystal to investigate the effect of strain rate on its nano-scale mechanical behavior. The load-indentation-depth curves, pop-in events, hardness and Young's moduli of an a-plane (112¯0) ZnO single crystal at different strain rates were investigated at the nano-scale level. The results indicated that, with the indentation depth increasing, the load increased gradually at each maximum indentation depth, , during the loading process. A distinct pop-in event occurred on each loading curve except that corresponding to the of 10 nm. The applied load at the same indentation depth increased with the increasing strain rate during the nanoindentation of the a-plane (112¯0) ZnO single crystal. The higher strain rate deferred the pop-in event to a higher load and deeper indentation depth, and made the pop-in extension width larger. The hardness showed reverse indentation size effect (ISE) before the pop-in, and exhibited normal ISE after the pop-in. Both the hardness and the Young's modulus of the a-plane (112¯0) ZnO single crystal increased with the increasing strain rate, exhibiting the positive strain-rate sensitivity.
在本研究中，对a面（112¯0）ZnO单晶在100 nm压痕深度内的三种不同应变速率下进行了纳米压痕试验，以研究应变速率对其纳米尺度力学行为的影响。在纳米尺度水平上研究了a面（112¯0）ZnO单晶在不同应变速率下的载荷-压痕深度曲线、压入事件、硬度和杨氏模量。结果表明，随着压痕深度增加，在加载过程中的每个最大压痕深度处，载荷逐渐增加。除对应于10 nm的情况外，每条加载曲线上都发生了明显的压入事件。在a面（112¯0）ZnO单晶的纳米压痕过程中，相同压痕深度下的外加载荷随应变速率的增加而增加。较高的应变速率将压入事件推迟到更高的载荷和更深的压痕深度，并使压入扩展宽度更大。硬度在压入前表现出反压痕尺寸效应（ISE），在压入后表现出正压痕尺寸效应。a面（112¯0）ZnO单晶的硬度和杨氏模量均随应变速率的增加而增加，表现出正应变速率敏感性。
