Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6482692 | Materials Today Nano | 2018 | 6 Pages |
Abstract
Because of the lower total number and density of defects in nanocrystals than those in their bulk counterparts, the elastic strain limits and the plastic deformation behaviors of the former can be very different from those of the latter. Furthermore, as the surface atomic ratio increases, a surface-dominant elastic and plastic deformation characteristic may appear in nanocrystal metals. The competition between nano-strengthening and surface effects thus determines the apparent mechanical behaviors of nanocrystal metals. In this study, we conducted a series of in situ atomic-resolution deformation experiments on high stacking fault energy platinum nanocrystals using an aberration-corrected high-resolution transmission electron microscope. From the direct in situ atomic-scale observations, we provided direct atomic-resolution plastic deformation mechanisms for the Pt nanocrystals of size ranging from 20 to â¼0.7Â nm. As the nanocrystal size decreased, a crossover occurred from dislocation slip-to dislocation-free-mediated plastic deformation. For nanocrystals of size above â¼6Â nm, the plastic deformation was dominated by full dislocation. However, for nanocrystals of diameters below â¼2Â nm, it was uncovered that the plastic deformation was dominated by the dislocation-free plastic deformation. In the elastic regime, the Pt nanocrystals reached a low elastic strain plateau by 1.5% when the size was 20 to â¼9Â nm. The elastic strain increased when the crystal size was below â¼9Â nm, and the Pt nanocrystals remained on the theoretical elastic strain limit plateau by above â¼7.0% when the crystal size was below â¼2Â nm
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Authors
L. Wang, J. Teng, Y. Wu, J. Zou, G. Yu, Z. Zhang, X. Han,