"Conjugate channeling" effect in dislocation core diffusion: carbon transport in dislocated BCC iron

Dislocation pipe diffusion seems to be a well-established phenomenon. Here we demonstrate an unexpected effect, that the migration of interstitials such as carbon in iron may be accelerated not in the dislocation line direction ξ, but in a conjugate diffusion direction. This accelerated random walk...

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Bibliographic Details
Published in:PloS one 2013-04, Vol.8 (4), p.e60586-e60586
Main Authors: Ishii, Akio, Li, Ju, Ogata, Shigenobu
Format: Article
Language:English
Subjects:
Bioengineering
Burgers vector
Carbon
Carbon - chemistry
Channeling
Chemistry
Crystallography
Diffusion
Diffusion effects
Dislocation
Dislocation loops
Dislocation mobility
Energy
Enthalpy
Interstitials
Iron
Iron - chemistry
Materials Science
Migration
Models, Chemical
Molecular dynamics
Molecular Dynamics Simulation
Point defects
Random walk
Science
Temperature
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Summary:Dislocation pipe diffusion seems to be a well-established phenomenon. Here we demonstrate an unexpected effect, that the migration of interstitials such as carbon in iron may be accelerated not in the dislocation line direction ξ, but in a conjugate diffusion direction. This accelerated random walk arises from a simple crystallographic channeling effect. c is a function of the Burgers vector b, but not ξ, thus a dislocation loop possesses the same everywhere. Using molecular dynamics and accelerated dynamics simulations, we further show that such dislocation-core-coupled carbon diffusion in iron has temperature-dependent activation enthalpy like a fragile glass. The 71° mixed dislocation is the only case in which we see straightforward pipe diffusion that does not depend on dislocation mobility.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0060586