Atomic scale visualizations of low-angle grain boundary mediated plasticity by coupled dislocation climb and glide in nanoporous gold

Grain boundaries (GBs), as a prevalent structural characteristic, play a crucial role in the deformation of nanoporous metals with nanosized grains and ligaments. However, the fundamental understanding of GB-mediated deformation is still lacking because the plastic behavior of discrete ligaments involving GBs remains to be unknown. Here, we report atomic scale visualizations of coupled GB dislocation climb and glide in nanoporous gold ligaments with low-angle GBs via in situ tensile straining inside a Cs-corrected transmission electron microscope. The zig-zag motion paths of GB dislocations are precisely determined by real-time tracking of the movements of dislocation cores. The concurrent climb and glide of the dislocation arrays are confined to a narrow GB region, greatly enhancing GB diffusion in the bicrystal ligament. Our findings of coupled dislocation climb and glide shine a light on the room-temperature deformation of nanoporous metals and provide a time-dependent atomic-level physical image for GB engineering.