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

• Published in: Acta materialia Vol. 57; no. 6; pp. 1966 - 1974
• Main Authors: Blum, W., Zeng, X.H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2009; Elsevier
• 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; Dislocation generation; Ultrafine grains; Strain rate sensitivity; Dynamic recovery; Hall–Petch effect; Dynamical recovery; Deformation; Mechanical properties; Hall effect; Modeling; Recovery; Dislocation; Hardening; Fine grain structure; Hall-Petch effect; Hall Petch relationship; Strain rate
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2008.12.041

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.