A study on the effects of twin boundaries and surface morphology on deformation behaviours of silver nanowires

Abstract

Nanoscale twin boundaries (TBs) and surface morphology play a significant role in the yield behaviour of nanowires (NWs). However, few studies have directly compared their effects on the mechanical response of metal NWs. In this article, the mechanical properties of three 〈1 1 1〉 silver NWs with a diameter of 12.2 nm are studied using molecular dynamics simulations. The 〈1 1 1〉 silver NWs are single crystalline rectangular NWs (SCNW), twinned rectangular NWs (TRNW) and faceted twinned NWs (FTNW), respectively. Comparing SCNW and the twinned NWs, we found that a superior combination of higher strength and elasticity was achieved in the twinned NWs by introducing the TBs in elastic region. Then, we also found that the yield strain of FTNW have a strong dependence on TB spacing. Furthermore, a comparison of the incipient plastic deformation between TRNW and FTNW has been made by monitoring defects evolution. To identify the defects evolution, a centrosymmetry parameter was defined and implemented in the self-developed program. And we also compared the effect of TB and surface morphology on mechanical response of three silver NWs. In general, it can be concluded that TBs significantly influence the mechanical properties of metallic NWs and it is more essential than surface morphology.