A simple dislocation model of deformation resistance of ultrafine-grained materials explaining Hall–Petch strengthening and enhanced strain rate sensitivity

A model is presented where the properties of ultrafine-grained (UFG) materials are explained in terms of the influence of high-angle boundaries on the rates at which dislocations are stored and recovered at the boundaries. The model reproduces the experimental observations that UFG materials reach a...

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Bibliographic Details
Published in:Acta materialia 2009-04, Vol.57 (6), p.1966-1974
Main Authors: Blum, W., Zeng, X.H.
Format: Article
Language:English
Subjects:
Applied sciences
Boundaries
Deformation resistance
Dislocation generation
Dislocation models
Dynamic recovery
Exact sciences and technology
Flow stress
Grain size
Hall–Petch effect
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metals. Metallurgy
Steady state
Strain rate sensitivity
Ultrafine grains
Yield strength
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Summary:A model is presented where the properties of ultrafine-grained (UFG) materials are explained in terms of the influence of high-angle boundaries on the rates at which dislocations are stored and recovered at the boundaries. The model reproduces the experimental observations that UFG materials reach a steady state where the deformation resistance is independent of strain, that the strain rate sensitivity of flow stress is relatively high and that the steady-state flow stress increases inversely with the square root of grain size. The model results are compared to experimental data for UFG Cu and nanostructured Ni.
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2008.12.041