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MM: Fachverband Metall- und Materialphysik

MM 41: Computational Materials Modelling VI - Dislocations

MM 41.2: Vortrag

Mittwoch, 2. April 2014, 11:45–12:00, IFW D

Effects of carbon interstitials on Fe dislocation core mobility using atomistic-continuum coupling — •Karthikeyan Chockalingam, Rebecca Janisch, and Alexander Hartmaier — ICAMS, Ruhr-Universität Bochum, Universitätsstr. 150, Bochum, Nordrhein-Westfalen 44801

Besides iron, carbon is the most significant alloying element in steel. It has been observed that carbon segregates to dislocation cores to form so-called Cottrell clouds. This is energetically favorable due to the low solubility of C in the iron matrix and the release of strain at the dislocation core. The carbon clouds pin the dislocations, resulting in an increase in yield strength. To better understand the influence of carbon on dislocation core mobility, its influence on edge and screw dislocation was investigated. We found that the relative increase in critical stress is higher for an edge dislocation than for a screw dislocation.

For this analysis we implemented an atomistic-continuum framework in which the dislocation core is modeled atomistically, and the material away from the dislocation a core is described in a continuum-elasticity finite-element approach. Thus, the atomistic domain is restricted to a small region around the core, resulting in a significant reduction of the number of atoms required to model a dislocation. Initially we use an embedded atom method (EAM) type potential for the interatomic interactions, but the coupled framework is not limited to a particular choice of interaction and can also be used in combination with ab-initio methods.