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    In situ atomistic observation of disconnectionmediated grain boundary migration

    Editor:yingwen Date:2019-03-04 Hits:128

    Qi Zhu, Guang Cao, Jiangwei Wang, Chuang Deng, Jixue Li, Ze Zhang & Scott X. Mao [Nature Communications]

    Shear-coupled grain boundary (GB) migration is of general significance in the deformation of anocrystalline and polycrystalline materials, but comprehensive understanding of the migration mechanism at the atomic scale remains largely lacking. Here, we systematically investigate the atomistic migration of 11(113) coherent GBs in gold bicrystals using a stateof-art in situ shear testing technique combined with molecular dynamic simulations. We show that shear-coupled GB migration can be realised by the lateral motion of layer-by-layer nucleated GB disconnections, where both single-layer and double-layer disconnections have important contributions to the GB migration through their frequent composition and decomposition. We further demonstrate that the disconnection-mediated GB migration is fully reversible in shear loading cycles. Such disconnection-mediated GB migration should represent a general deformation phenomenon in GBs with different structures in polycrystalline and nanocrystalline materials, where the triple junctions can act as effective nucleation sites of GB disconnections.

    https://doi.org/10.1038/s41467-018-08031-x

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