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Dislocation motion in tungsten: Atomistic input to discrete dislocation simulations

: Srivastava, K.; Gröger, R.; Weygand, D.; Gumbsch, P.

Preprint urn:nbn:de:0011-n-2545701 (1.6 MByte PDF)
MD5 Fingerprint: 803b8a17737584b959a541eac9c60422
Created on: 23.5.2014

International Journal of Plasticity 47 (2013), pp.126-142
ISSN: 0749-6419
Deutsche Forschungsgemeinschaft DFG
Gu 367/30
Journal Article, Electronic Publication
Fraunhofer IWM ()

A computational framework for the discrete dislocation dynamics simulation of body-centered cubic (bcc) metals which incorporates atomistic simulation results is developed here on the example of tungsten. Mobility rules for the a/2111 screw dislocations are based on the kink-pair mechanism. The fundamental physical quantity controlling the kink-pair nucleation, the stress-dependent activation enthalpy, is obtained by fitting the line-tension model to atomistic data extending the approach by Gröger et al. (2008a,b) and Gröger and Vitek (2008c). In agreement with atomistic simulation, kink-pair nucleation is assumed to occur only on {110} planes. It is demonstrated that slip of the crystal along high-index planes like {112} which is often observed in experiments is obtained by the glide of the dislocation on two or more {110} planes. It is shown that such an atomistic based description of the dislocation mobility provides a physical basis to naturally explain many experim entally observed phenomena in bcc metals like the tension-compression asymmetry, the orientation dependence of loading, temperature dependence of yield stress and the crystallography of slip.