Effect of Strain Rate on Nano-Scale Mechanical Behavior of A-Plane (112¯0) ZnO Single Crystal by Nanoindentation

Xiaolin Zhu; Jijun Li; Lihua Zhang; Fengchao Lang; Xiaohu Hou; Xueping Zhao; Weiguang Zhang; Chunwang Zhao; Zijian Yang

doi:10.3390/mi14020404

Effect of Strain Rate on Nano-Scale Mechanical Behavior of A-Plane (112¯0) ZnO Single Crystal by Nanoindentation

Micromachines (Basel). 2023 Feb 8;14(2):404. doi: 10.3390/mi14020404.

Authors

Xiaolin Zhu^{1

2

3}, Jijun Li^{1

2}, Lihua Zhang⁴, Fengchao Lang¹, Xiaohu Hou⁵, Xueping Zhao⁵, Weiguang Zhang¹, Chunwang Zhao⁶, Zijian Yang¹

Affiliations

¹ College of Science, Inner Mongolia University of Technology, Hohhot 010051, China.
² School of Mechanical and Energy Engineering, Shanghai Technical Institute of Electronics & Information, Shanghai 201411, China.
³ College of Science and Technology, Inner Mongolia Open University, Hohhot 010011, China.
⁴ College of Arts and Sciences, Shanghai Maritime University, Shanghai 201306, China.
⁵ Test Center, Inner Mongolia University of Technology, Hohhot 010051, China.
⁶ School of Materials Science and Hydrogen Energy, Foshan University, Foshan 528000, China.

Abstract

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, h_ma, during the loading process. A distinct pop-in event occurred on each loading curve except that corresponding to the h_max 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.

Keywords: Young’s modulus; a-plane ( 11 2 ¯ 0 ) ZnO single crystal; hardness; load–indentation-depth curve; nano-scale mechanical behavior; nanoindentation; pop-in; strain rate.

Abstract

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