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Nanoindentation pop‐in in oxides at room temperature: Dislocation activation or crack formation?

Fang, Xufei ; Bishara, Hanna ; Ding, Kuan ; Tsybenko, Hanna ; Porz, Lukas ; Höfling, Marion ; Bruder, Enrico ; Li, Yingwei ; Dehm, Gerhard ; Durst, Karsten (2023):
Nanoindentation pop‐in in oxides at room temperature: Dislocation activation or crack formation? (Publisher's Version)
In: Journal of the American Ceramic Society, 104 (9), pp. 4728-4741. Wiley, e-ISSN 1551-2916,
DOI: 10.26083/tuprints-00023199,
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Item Type: Article
Origin: Secondary publication service
Status: Publisher's Version
Title: Nanoindentation pop‐in in oxides at room temperature: Dislocation activation or crack formation?
Language: English
Abstract:

Most oxide ceramics are known to be brittle macroscopically at room temperature with little or no dislocation-based plasticity prior to crack propagation. Here, we demonstrate the size-dependent brittle to ductile transition in SrTiO₃ at room temperature using nanoindentation pop-in events visible as a sudden increase in displacement at nominally constant load. We identify that the indentation pop-in event in SrTiO₃ at room temperature, below a critical indenter tip radius, is dominated by dislocation-mediated plasticity. When the tip radius increases to a critical size, concurrent dislocation activation and crack formation, with the latter being the dominating process, occur during the pop-in event. Beyond the experimental examination and theoretical justification presented on SrTiO₃ as a model system, further validation on α-Al₂O₃, BaTiO₃, and TiO₂ are briefly presented and discussed. A new indentation size effect, mainly for brittle ceramics, is suggested by the competition between the dislocation-based plasticity and crack formation at small scale. Our finding complements the deformation mechanism in the nano-/microscale deformation regime involving plasticity and cracking in ceramics at room temperature to pave the road for dislocation-based mechanics and functionalities study in these materials.

Journal or Publication Title: Journal of the American Ceramic Society
Volume of the journal: 104
Issue Number: 9
Place of Publication: Darmstadt
Publisher: Wiley
Uncontrolled Keywords: crack formation, dislocation, nanoindentation pop-in, oxide, size effect
Classification DDC: 500 Naturwissenschaften und Mathematik > 530 Physik
500 Naturwissenschaften und Mathematik > 540 Chemie
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
Date Deposited: 10 Feb 2023 09:20
Last Modified: 25 May 2023 06:08
DOI: 10.26083/tuprints-00023199
Corresponding Links:
URN: urn:nbn:de:tuda-tuprints-231998
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/23199
PPN: 507930770
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