Dislocation-mediated shear amorphization in boron carbide

Kolan Madhav Reddy, Dezhou Guo, Shuangxi Song, Chun Cheng, Jiuhui Han, Xiaodong Wang, Qi An, Mingwei Chen

Research output: Contribution to journalArticlepeer-review

Abstract

The failure of superhard materials is often associated with stress-induced amorphization. However, the underlying mechanisms of the structural evolution remain largely unknown. Here, we report the experimental measurements of the onset of shear amorphization in single-crystal boron carbide by nanoindentation and transmission electron microscopy. We verified that rate-dependent loading discontinuity, i.e., pop-in, in nanoindentation load-displacement curves results from the formation of nanosized amorphous bands via shear amorphization. Stochastic analysis of the pop-in events reveals an exceptionally small activation volume, slow nucleation rate, and lower activation energy of the shear amorphization, suggesting that the high-pressure structural transition is activated and initiated by dislocation nucleation. This dislocation-mediated amorphization has important implications in understanding the failure mechanisms of superhard materials at stresses far below their theoretical strengths.

Original languageEnglish
Article numbereabc6714
JournalScience Advances
Volume7
Issue number8
DOIs
Publication statusPublished - 2021 Feb 17

ASJC Scopus subject areas

  • General

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