"Conjugate Channeling" Effect in Dislocation Core Diffusion: Carbon Transport in Dislocated BCC Iron

• Main Authors: Ishii, Akio (Author), Li, Ju (Contributor), Ogata, Shigenobu (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Materials Science and Engineering (Contributor), Massachusetts Institute of Technology. Department of Nuclear Science and Engineering (Contributor)
• Format: Article
• Language: English
• Published: Public Library of Science, 2013-11-20T22:05:00Z.
• Subjects: Article
• Online Access: Get fulltext

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 [symbol], 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 [symbol], 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.
National Science Foundation (U.S.) (Grant No. CMMI-0728069)
National Science Foundation (U.S.) (Grant No. DMR-1008104)
National Science Foundation (U.S.) (Grant No. DMR-1120901)