The elastic–plastic transition in nanoparticle collisions
When nanoparticles (NPs) collide with low velocities, they interact elastically in the sense that – besides their fusion caused by their mutual van-der-Waals attraction – no defects are generated. We investigate the minimum velocity, vc, necessary for generating defects and inducing plasticity in the NP. The determination of this elastic–plastic threshold is of prime importance for modeling the behavior of granular matter. Using the generic Lennard-Jones interaction potential, we find vc to increase strongly with decreasing radius. Current models do not agree with our simulations, but we provide a model based on dislocation emission in the contact zone that quantitatively describes the size dependence of the elastic–plastic transition.