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Nucleation of amorphous shear bands at nanotwins in boron suboxide

An, Qi and Reddy, K. Madhav and Qian, Jin and Hemker, Kevin J. and Chen, Ming-Wei and Goddard, William A., III (2016) Nucleation of amorphous shear bands at nanotwins in boron suboxide. Nature Communications, 7 (3). Art. No. 11001. ISSN 2041-1723. PMCID PMC4804168.

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The roles of grain boundaries and twin boundaries in mechanical properties are well understood for metals and alloys. However, for covalent solids, their roles in deformation response to applied stress are not established. Here we characterize the nanotwins in boron suboxide (B_6O) with twin boundaries along the {0111} planes using both scanning transmission electron microscopy and quantum mechanics. Then, we use quantum mechanics to determine the deformation mechanism for perfect and twinned B_6O crystals for both pure shear and biaxial shear deformations. Quantum mechanics suggests that amorphous bands nucleate preferentially at the twin boundaries in B_6O because the twinned structure has a lower maximum shear strength by 7.5% compared with perfect structure. These results, which are supported by experimental observations of the coordinated existence of nanotwins and amorphous shear bands in B_6O, provide a plausible atomistic explanation for the influence of nanotwins on the deformation behaviour of superhard ceramics.

Item Type:Article
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URLURL TypeDescription CentralArticle
An, Qi0000-0003-4838-6232
Qian, Jin0000-0002-0162-0477
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2016 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit Received 19 October 2015; Accepted 09 February 2016; Published 22 March 2016. This work was supported by the Defense Advanced Research Projects Agency (W31P4Q-13-1-0010, program managers, Judah Goldwasser and John Paschkewitz), by the Army Research Laboratory under Cooperative Agreement Number W911NF-12-2-0022 and by the National Science Foundation (DMR-1436985, program manager, John Schlueter). The experimental work was carried out at WPI-AIMR, Tohoku University, Japan, with research supported by the ‘World Premier International (WPI) Center Initiative Atoms, Molecules and Materials’, MEXT, Japan. We thank Professor Goto of IMR at the Tohoku University for providing as-synthesized B6O sample for experimental observations. We thank Dr Kelvin Xie in the Johns Hopkins University for useful discussion. These authors contributed equally to this work: K. Madhav Reddy & Jin Qian. Author contributions: Q.A., K.M.R. and W.A.G. wrote the manuscript. Q.A. and J.Q. performed the QM simulations and K.M.R. conducted the TEM characterization and performed image simulation. Q.A., K.M.R., K.H., M.-W.C. and W.A.G. analysed the data and discussed the results. All authors commented on the manuscript. The authors declare no competing financial interests.
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Defense Advanced Research Projects Agency (DARPA)W31P4Q-13-1-0010
Army Research LaboratoryW911NF-12-2-0022
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Issue or Number:3
PubMed Central ID:PMC4804168
Record Number:CaltechAUTHORS:20160328-100333882
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Official Citation:An, Q. et al. Nucleation of amorphous shear bands at nanotwins in boron suboxide. Nat. Commun. 7:11001 doi: 10.1038/ncomms11001 (2016)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65694
Deposited By: Tony Diaz
Deposited On:30 Mar 2016 19:35
Last Modified:09 Mar 2020 13:19

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