The
mechanical stability of metallic nanomaterials has been intensively
studied due to their unique structures and promising applications.
Although extensive investigations have been carried out on the deformation
behaviors of metallic nanomaterials, the atomic-scale deformation
mechanism of metallic nanomaterials with unconventional hexagonal
structures remains unclear because of the lack of direct experimental
observation. Here, we conduct an atomic-resolution in situ tensile-straining
transmission electron microscopy investigation on the deformation
mechanism of gold nanoribbons with the 4H (hexagonal) phase. Our results
reveal that plastic deformation in the 4H gold nanoribbons comprises
three stages, in which both full and partial dislocations are involved.
At the early deformation stage, plastic deformation is governed by
full dislocation activities. Partial dislocations are subsequently
activated in regions that have undergone full dislocation gliding,
leading to phase transformation from the 4H phase to the face-centered
cubic (FCC) phase. At the last stage of the deformation process, the
volume fraction of the FCC phase increases, and full dislocation activities
in the FCC regions also play an important role.