Reveal the size effect on the plasticity of ultra-small sized Ag nanowires with in situ atomic-scale microscopy

Abstract

Revealing the atomic-scale deformation mechanisms of metallic nanowires (NWs) is important for their practical application. However, there are few reports providing direct atomic-scale experimental elucidation on those metallic NWs. Here, we conduct serial in situ deformation tests on silver (Ag) nanowires with diameters of 3–11 nm. The in situ atomic-scale observations reveal a transition in the deformation mechanism with a decrease in the diameter of Ag NWs. For the [55¯4] and [001] oriented NWs with diameters of ∼11 nm, the plastic deformation is dominated by full dislocation that involves leading and trailing partial dislocations, whereas the full or extended dislocations are rarely observed in the NWs with diameters in the range of ∼ 5–8 nm, and their plastic deformation is governed by SF generation and annihilation. Moreover, for the [1¯11] oriented NWs, 60° mixed and pure edge dislocations are frequently observed when the diameter is approximately 5 nm and the plastic deformation is accommodated by relative slip between two adjacent {111} planes for NWs with diameters below ∼ 3 nm. These results indicate that the plastic deformation not only depends on the size of NWs but also can be significantly impacted by the loading orientation.