The elastic–plastic transition in nanoparticle collisions

Abstract

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.

Collision‐Induced Melting in Collisions of Water Ice Nanograins: Strong Deformations and Prevention of Bouncing

“…We observe maximum pressures of 0.3, 0.45, and 1.2 GPa for v = 150, 300, 625 m/s. We can estimate the pressures occurring during collision from the law p = ρ v c l ; this relationship originates from an appropriate simplification of the Hugoniot relationship (Millán et al, ). It predicts collision pressures of 0.5, 1.1, 2.2 GPa for the three velocities.…”

“…MD has been used previously to characterize the result of collisions of nanometer‐sized grains, mostly for generic interactions such as modeled by the Lennard‐Jones potential (Tanaka et al, ; Millán et al, , ). Recently, simulations of silica grain collisions confirmed the gross trends predicted by JKR theory in the nanoscale regime but pointed at systematic deviations caused by intergrain attractions (Nietiadi et al, ).…”

Orientation-dependent properties of nanoparticle impact

“…Recently, Millán et al [18,19] studied the critical velocity for elastic-plastic transition of nanoparticle impacts. Their work succeeds in finding a dislocation-emission based model that is able to describe their simulation results.…”

Influence of Elastic Stiffness and Surface Adhesion on Bouncing of Nanoparticles

“…For higher velocities, v >100 m/s, and compliant spheres, dislocations were formed transiently but disappeared again after the collision. We note that during the collision of similarly sized crystalline nanospheres interacting via the generic Lennard-Jones potential, ample dislocation production could be detected [ 22 , 23 ], while shear transformation zones were identified in the collision of amorphous silica spheres [ 7 ], both collision systems thus exhibit plasticity. In our case, the high elastic moduli prevent the establishment of plastic deformation; inelastic energy losses are caused only by the excitation of vibrations in the collided spheres.…”