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 ∼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 {1 1 1} 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.