Ultrahigh plastic flow in Au nanotubes enabled by surface stress facilitated reconstruction

Metal nanowires are usually strong but are not able to maintain a high plastic flow due to a lack of strain hardening. In this study, we investigated the tensile deformation of a new category of metal nanowires with hollow interiors by atomistic simulations - the so-called metal nanotubes - and revealed that they possess a combination of ultrahigh strength and plastic flow. In particular, it was found that by controlling the wall thickness and axial orientation, ultrahigh plastic flow stress of more than 2 GPa could be maintained at up to similar to 60% tensile strain in Au nanotubes, whereas the solid Au nanowires of similar size yielded at tensile strain of less than 5%, after which the stress dropped immediately below 1 GPa. Furthermore, a universal trend of surface reconstruction to the energetically favorable close-packed {111} orientation was found in Au nanotubes regardless of the initial orientation, which may be responsible for the unique plasticity in Au nanotubes with extremely thin walls. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.