Molecular Dynamics Simulations of Compression-Tension Asymmetry in Plasticity of Fe Nanopillars

TL;DR

This study uses molecular dynamics simulations to investigate the tension-compression asymmetry in plasticity of bcc Fe nanopillars, revealing distinct deformation mechanisms—dislocation glide in compression and twinning in tension—that explain experimental observations.

Contribution

It demonstrates the different deformation mechanisms in bcc Fe nanopillars under tension and compression through molecular dynamics simulations, providing insight into the asymmetry in plasticity.

Findings

Dislocation glide dominates in compression.

Twinning is the primary mechanism in tension.

The deformation mechanisms explain the observed asymmetry.

Abstract

Tension-compression asymmetry is a notable feature of plasticity in bcc single crystals. Recent experiments reveal striking differences in the plasticity of bcc nanopillars for tension and compression. Here we present results from molecular dynamics simulations of nanopillars of bcc Fe in tension and compression. We find that a totally different deformation mechanism applies in each cases: dislocation glide in compression and twinning in tension. This difference explains experimentally-observed asymmetry in the nanopillar morphology.