Independence of slip velocities on applied stress in small crystals

R. Maaß, P. M. Derlet, J. R. Greer

Research output: Contribution to journalArticlepeer-review

Abstract

Directly tracing the spatiotemporal dynamics of intermittent plasticity at the micro-and nanoscale reveals that the obtained slip dynamics are independent of applied stress over a range of up to ∼400 MPa, as well as being independent of plastic strain. Whilst this insensitivity to applied stress is unexpected for dislocation plasticity, the stress integrated statistical properties of both the slip size magnitude and the slip velocity follow known theoretical predictions for dislocation plasticity. Based on these fi ndings, a link between the crystallographic slip velocities and an underlying dislocation avalanche velocity is proposed. Supporting dislocation dynamics simulations exhibit a similar regime during microplastic fl ow, where the mean dislocation velocity is insensitive to the applied stress. Combining both experimental and modeling observations, the results are discussed in a framework that fi rmly places the plasticity of nano-and micropillars in the microplastic regime of bulk crystals.

Original languageEnglish (US)
Pages (from-to)341-351
Number of pages11
JournalSmall
Volume11
Issue number3
DOIs
StatePublished - Jan 21 2015
Externally publishedYes

Keywords

  • Intermittent flow
  • Microplasticity
  • Size effects
  • Slip velocity

ASJC Scopus subject areas

  • Engineering (miscellaneous)
  • General Chemistry
  • General Materials Science
  • Biotechnology
  • Biomaterials

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