This week I am attending MMM11 conference with a poster and a presentation

Venue: The 11th International Conference on Multiscale Materials Modeling

Kinetics and ordering of hydrogen at dislocations in bcc iron

Authors: Petr Grigorev, Philippe Maugis

Date: Wednesday September 25, 16:50 - 18:50

Location: Forum Hall Foyer 3

download the poster

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Hybrid QM/ML study of carbon induced screw dislocation pinning in tungsten

Authors: Petr Grigorev, Emmanuel Clouet, Mihai-Cosmin Marinica, Thomas D. Swinburne, Lisa Ventelon

Date: Wednesday September 25, 13:50 - 14:10

Symposium: C. Multiscale modelling of crystal plasticity of materials

Location: South Hall 3C

Abstract:

Interaction of solute impurities with dislocations are one of the main mechanisms of solute solution strengthening. Atomistic modelling of these phenomena by ab initio methods is hindered size limitations. This work addresses these limitations by exploiting recent developments in hybrid quantum mechanics/machine learning (QM/ML) simulation methods, which use ML potentials as highly adaptive medium in which ab initio conditions can be embedded . The results showed that carbon stabilises the hard core dislocation configuration with slow relaxation back to the easy core in agreement with ab initio results of . Long range relaxation of the dislocation line back to the easy core occurs at the distance of ~10 Burgers vectors and consistent with results of . When dislocation is one Peierls valley away from the C atom it goes back almost to perfect straight line while C goes to octahedral position which is the stable position for C in perfect material . This contrasts to what was seen for C in Fe in where in order to unpin from a carbon atom dislocation had to move two Peierls valleys away. Despite pronounced core effect, the minimum energy path for the dislocation to move away from the C atom does not show additional pinning barrier.