期刊
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
卷 65, 期 -, 页码 54-68出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmps.2014.01.004
关键词
Kinkpair; BCC Iron; Screw dislocation; Crystal plasticity; Nudged elastic band method
资金
- DOE Office of Nuclear Energy's Nuclear Energy University Programs (NEUP)
The mobility of dislocation in body-centered cubic (BCC) metals is controlled by the thermally activated nucleation of kinks along the dislocation core. By employing a recent interatomic potential and the Nudged Elastic Band method, we predict the atomistic saddle-point state of 1/2(111) screw dislocation motion in BCC iron that involves the nucleation of correlated kinkpairs and the resulting double superkinks. This unique process leads to a single-humped minimum energy path that governs the one-step activation of a screw dislocation to move into the adjacent (110) Peierls valley, which contrasts with the double-humped energy path and the two-step transition predicted by other interatomic potentials. Based on transition state theory, we use the atomistically computed, stress-dependent kinkpair activation parameters to inform a coarse-grained crystal plasticity flow rule. Our atomistically-informed crystal plasticity model quantitatively predicts the orientation dependent stress-strain behavior of BCC iron single crystals in a manner that is consistent with experimental results. The predicted temperature and strain-rate dependencies of the yield stress agree with experimental results in the 200350 K temperature regime, and are rationalized by the small activation volumes associated with the kinkpair-mediated motion of screw dislocations. (C) 2014 Elsevier Ltd. All rights reserved.
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