Mechanical behaviors of single crystalline and fivefold twinned Ag nanowires under compression

Abstract

The mechanical behaviors of fivefold twinned (FT) Ag nanowires under compression are investigated by molecular dynamics simulations. As a comparison, the single crystalline (SC) nanowires are also investigated. The fivefold twin boundary strengthens not only the tensile yield strength but also the compressive yield strength, suggesting the initial stress distribution is not the main factor behind the strengthening. The modulus-based explanation is also found invalid since similar modulus is observed between these two types of nanowires. In contrast to “dislocation starvation” state observed in SC nanowires under compression, the addition of fivefold twin boundary into nanowires leads to complex dislocation–dislocation and dislocation–twin interactions, contributing to increased dislocation density. While extend dislocation slip dominates the plastic deformation in SC nanowires, generation of {001}〈110〉 Lomer dislocations and their subsequent cross-slip are found to be the dominant deformation mechanisms in FT Ag nanowires under compression. Effects of boundary condition and sample geometry on plastic deformation behaviors are also investigated.