Stress dependence of the Peierls barrier of 1/2111 screw dislocations in BCC metals

0395120 - ÚFM 2014 RIV GB eng J - Journal Article
Gröger, Roman - Vitek, V.
Stress dependence of the Peierls barrier of 1/2111 screw dislocations in BCC metals.
Acta Materialia. Roč. 61, č. 17 (2013), s. 6362-6371. ISSN 1359-6454. E-ISSN 1873-2453
R&D Projects: GA MŠMT(CZ) ED1.1.00/02.0068; GA ČR GAP204/10/0255
Institutional support: RVO:68081723
Keywords : Screw dislocation * Peierls barrier * Nudged elastic band * BCC metals * Peierls stress
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.940, year: 2013

The recently formulated constrained nudged elastic band method with atomic relaxations (NEB + r) (Gröger R, Vitek V. Model Simul Mater Sci Eng 2012;20:035019) is used to investigate the dependence of the Peierls barrier of 1/2111 screw dislocations in body-centered cubic metals on non-glide stresses. These are the shear stresses parallel to the slip direction acting in the planes of the 111 zone different from the slip plane, and the shear stresses perpendicular to the slip direction. Both these shear stresses modify the structure of the dislocation core and thus alter both the Peierls barrier and the related Peierls stress. Understanding of this effect of loading is crucial for the development of mesoscopic models of thermally activated dislocation motion via formation and propagation of pairs of kinks. The Peierls stresses and related choices of the glide planes determined from the Peierls barriers agree with the results of molecular statics calculations (Gröger R, Bailey AG, Vitek V. Acta Mater 2008;56:5401), which demonstrates that the NEB + r method is a reliable tool for determining the variation in the Peierls barrier with the applied stress. However, such calculations are very time consuming, and it is shown here that an approximate approach of determining the stress dependence of the Peierls barrier (proposed in Gröger R, Vitek V. Acta Mater 2008;56:5426) can be used, combined with test calculations employing the NEB + r method.
Permanent Link: http://hdl.handle.net/11104/0231011