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Independence of Slip Velocities on Applied Stress in Small Crystals
Author(s) -
Maaß R.,
Derlet P. M.,
Greer J. R.
Publication year - 2015
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201400849
Subject(s) - plasticity , materials science , slip (aerodynamics) , dislocation , mechanics , nanoscopic scale , dislocation creep , stress (linguistics) , flow stress , condensed matter physics , composite material , nanotechnology , strain rate , physics , thermodynamics , linguistics , philosophy
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 findings, 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 flow, 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 firmly places the plasticity of nano‐ and micropillars in the microplastic regime of bulk crystals.