Size-Dependent Tensile Behavior and Dislocation Dynamics in Cu and Ag Nanowires: A Molecular Dynamics Study

TL;DR

This study uses molecular dynamics simulations to explore how copper and silver nanowires deform under tension, revealing size-dependent strength differences and the critical role of dislocations in their plastic behavior.

Contribution

It provides new insights into the size-dependent mechanical properties and dislocation mechanisms in Cu and Ag nanowires through atomistic simulations.

Findings

Silver nanowires are stiffer and have higher yield points than copper wires.

Reducing nanowire diameter increases strength due to surface atom effects.

Dislocations, especially surface-initiated ones, dominate plastic deformation and fracture.

Abstract

By using molecular dynamics simulations, the research examine how copper and silver nanowires respond to tensile loading in order to clarify their nanoscale deformation mechanisms. The results demonstrate that these two metal nanowires follow notably different stress - strain trends, with silver wires exhibiting greater elastic stiffness and higher yield points at equivalent diameters - an effect likely rooted in silver's stronger atomic bonding and more stable microstructure. A pronounced size effect is observed: as the wire diameter diminishes, both the yield strength and ultimate tensile strength increase substantially, a behavior driven by the higher proportion of surface atoms that enhance dislocation nucleation and mobility. Atomistic analyses further underscore the dominant role of dislocations during plastic deformation, and in particular reveal that surface - initiated dislocations in thinner wires critically affect their fracture behavior.