Atomistic dynamics of disconnection-me diate d grain boundary plasticity: A case study of gold nanocrystals

Grain boundary (GB) mediated deformation is a vital contributor to the plasticity of polycrystalline ma-terials, where the disconnection model has become a widely recognized approach to depict the GB dy-namics. However, experimental understanding of the atomistic disconnection dynamics remains scarce. In this case study of gold nanocrystals, atomistic disconnection dynamics governing the shear-coupled migration of flat GBs have been systematically investigated via in situ transmission electron microscopy nanomechanical testing supported by molecular dynamics simulations. Specifically, the site-dependent nucleation, shear-driven propagation, and diverse interactions associated with distinct GB disconnec-tions are systematically elucidated and quantitatively compared. Moreover, the disconnection-mediated GB plasticity proves to prevail among different tilt and mixed GBs in gold. Eventually, a conceptual map of disconnection-mediated GB dynamics is established, which would furnish a unified understanding of GB plasticity in metallic materials. (c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.