TY - JOUR
T1 - Dislocation-mediated shear amorphization in boron carbide
AU - Reddy, Kolan Madhav
AU - Guo, Dezhou
AU - Song, Shuangxi
AU - Cheng, Chun
AU - Han, Jiuhui
AU - Wang, Xiaodong
AU - An, Qi
AU - Chen, Mingwei
N1 - Funding Information:
This work was sponsored by the MOST 973 of China (grant no. 2015CB856800), the National Natural Science Foundation of China (grant nos. 11327902, 51271113, 11704245, 51821001, and 51850410501), and the fusion research program of "World Premier International Research Center (WPI) Initiative" by MEXT, Japan. M.C. was sponsored by the Whiting School of Engineering, the Johns Hopkins University, and the NSF (NSF NSF-DMR-1804320).
Publisher Copyright:
Copyright © 2021 The Authors, some rights reserved.
PY - 2021/2/17
Y1 - 2021/2/17
N2 - 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.
AB - 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.
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U2 - 10.1126/sciadv.abc6714
DO - 10.1126/sciadv.abc6714
M3 - Article
C2 - 33597237
AN - SCOPUS:85101363327
VL - 7
JO - Science advances
JF - Science advances
SN - 2375-2548
IS - 8
M1 - eabc6714
ER -