Anisotropic Deformation in the Compressions of Single Crystalline Copper Nanoparticles

TL;DR

This study uses atomistic simulations to explore how single crystalline copper nanoparticles deform anisotropically under compression, revealing different deformation mechanisms depending on surface configuration and crystallographic orientation.

Contribution

It provides detailed insights into the anisotropic deformation mechanisms of metallic nanoparticles, highlighting the role of surface steps, dislocation activity, and twin boundary migration.

Findings

Elastic behavior matches Hertzian or flat punch models depending on surface configuration.

Dislocation nucleation varies with crystallographic orientation, involving glide, nucleation, and twin boundary migration.

Plastic deformation mechanisms are orientation-dependent, affecting mechanical property extraction.

Abstract

Atomistic simulations are performed to probe the anisotropic deformation in the compressions of face-centred-cubic metallic nanoparticles. In the elastic regime, the compressive load-depth behaviors can be characterized by the classical Hertzian model or flat punch model, depending on the surface configuration beneath indenter. On the onset of plasticity, atomic-scale surface steps serve as the source of heterogeneous dislocation in nanoparticle, which is distinct from indenting bulk materials. Under [111] compression, the gliding of jogged dislocation takes over the dominant plastic deformation. The plasticity is governed by nucleation and exhaustion of extended dislocation ribbons in [110] compression. Twin boundary migration mainly sustain the plastic deformation under [112] compression. This study is helpful to extract the mechanical properties of metallic nanoparticles and understand their anisotropic deformation behaviors.