Thompson, DH, Tarleton, E, Roberts, SG et al. (1 more author) (2018) Interstitial-mediated dislocation climb and the weakening of particle-reinforced alloys under irradiation. Physical Review Materials, 2 (8). 080601. ISSN 2475-9953
Abstract
Dislocations can climb out of their glide plane by absorbing (or emitting) point defects [vacancies and self-interstitial atoms (SIAs)]. In contrast with conservative glide motion, climb relies on the point defects' thermal diffusion and hence operates on much longer timescales, leading to some forms of creep. While equilibrium point defect concentrations allow dislocations to climb to relieve nonglide stresses, point defect supersaturations also lead to osmotic forces, driving dislocation motion even in the absence of external stresses. Self-interstitial atoms typically have significantly higher formation energies than vacancies, so their contribution to climb is usually ignored. However, under irradiation conditions, both types of defect are athermally created in equal numbers. In this paper, we use simple thermodynamic arguments to show that the contribution of interstitials cannot be neglected in irradiated materials and that the osmotic force they induce on dislocations is many orders of magnitude larger than that caused by vacancies. This explains why the prismatic dislocation loops observed by in situ transmission electron microscope irradiations are more often of interstitial rather than vacancy character. Using discrete dislocation dynamics simulations, we investigate the effect on dislocation-obstacle interactions and find reductions in the depinning time of many orders of magnitude. This has important consequences for the strength of particle-reinforced alloys under irradiation.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | ©2018 American Physical Society. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | Creep; Crystal defects; Disclinations & dislocations; Interstitials; Material failure; Plastic deformation; Plasticity |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 05 Sep 2018 08:05 |
Last Modified: | 04 Dec 2018 20:09 |
Status: | Published |
Publisher: | American Physical Society |
Identification Number: | 10.1103/PhysRevMaterials.2.080601 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:134737 |