Surface Adatom Diffusion-Assisted Dislocation Nucleation in Metal Nanowires

We employ a hybrid diffusion- and nucleation-based kineticMonteCarlo model to elucidate the significant impact of adatom diffusionon incipient surface dislocation nucleation in metal nanowires. Wereveal a stress-regulated diffusion mechanism that promotes preferentialaccumulation of diffusing adatoms near nucleation sites, which explainsthe experimental observations of strong temperature but weak strain-ratedependence as well as temperature-dependent scatter of the nucleationstrength. Furthermore, the model demonstrates that a decreasing rateof adatom diffusion with an increasing strain rate will lead to stress-controllednucleation being the dominant nucleation mechanism at higher strainrates. Overall, our model offers new mechanistic insights into howsurface adatom diffusion directly impacts the incipient defect nucleationprocess and resulting mechanical properties of metal nanowires.