Nucleation of amorphous shear bands at nanotwins in boron suboxide

Qi An, K. Madhav Reddy, Jin Qian, Kevin J. Hemker, Ming Wei Chen, William A. Goddard

    Research output: Contribution to journalArticlepeer-review

    23 Citations (Scopus)

    Abstract

    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 (B6O) with twin boundaries along the {01¯11} planes using both scanning transmission electron microscopy and quantum mechanics. Then, we use quantum mechanics to determine the deformation mechanism for perfect and twinned B6O crystals for both pure shear and biaxial shear deformations. Quantum mechanics suggests that amorphous bands nucleate preferentially at the twin boundaries in B6O 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 B6O, provide a plausible atomistic explanation for the influence of nanotwins on the deformation behaviour of superhard ceramics.

    Original languageEnglish
    Article number11001
    JournalNature communications
    Volume7
    DOIs
    Publication statusPublished - 2016 Mar 22

    ASJC Scopus subject areas

    • Chemistry(all)
    • Biochemistry, Genetics and Molecular Biology(all)
    • Physics and Astronomy(all)

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