Journal
ACTA MATERIALIA
Volume 58, Issue 17, Pages 5797-5805Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2010.06.055
Keywords
Al alloy; Guinier-Preston zones; Precipitation hardening; Atomistic simulation; Dislocation-obstacle interaction
Funding
- NASA [NNX08BA39A]
- NASA [NNX08BA39A, 90532] Funding Source: Federal RePORTER
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The interaction of dislocations with Guinier-Preston (GP) zones is a process that contributes to the yield strength of many underaged precipitate-strengthened alloys. Here we use atomistic modeling to investigate this process in an Al-Cu alloy using a newly developed interatomic potential. The study focuses on edge dislocation interactions in the athermal limit. The critical shear stress and the mechanism by which dislocations overcome GP zones is found to vary significantly depending upon GP zone size, orientation and offset from the dislocation glide plane. Dislocation cutting, looping, leading partial cutting with trailing partial looping, diffusionless climb and defect nucleation at the dislocation-GP zone contact point are all observed. In the majority of cases dislocation looping is the controlling mechanism, challenging the applicability of traditional continuum dislocation cutting models to the underaged Al-Cu system at 0 K. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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