Year: 2012
Type: preprint
Abstract: We perform atomistic computer simulations to study the mechanism of homogeneous dislocation nucleation in two dimensional (2D) hexagonal crystalline films during indentation with a circular nanoindenter. The nucleation process is governed by the vanishing of the energy associated with a single normal mode. This critical mode is largely confined to a single plane of adjacent atoms. For fixed film thickness, L, the spatial extent, ξ, of the critical mode grows with indenter radius, R. For fixed R/L, the spatial extent ξ, grows roughly as ξ~ L^0.4. We, furthermore, perform a mesoscale analysis to determine the lowest energy normal mode for mesoscale regions of varying radius, r_{meso}, centered on the critical mode's core. The energy, λ_{meso}, of the lowest normal mode in the meso-region decays very rapidly with r_{meso} and λ_{meso} ~= 0 for r_{meso} >~ ξ. The lowest normal mode shows a spatial extent, ξ_{meso}, which has a sublinear power-law increase with r_{meso} for r_{meso} ~ 1.5 ξ. In this sense homogeneous dislocation nucleation should be understood as a quasi-local phenomenon.
Source: arXiv (Cornell University)
Authors: Hasan, Asad, Maloney, Craig E.
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1824524740