Bulletin of the American Physical Society
APS March Meeting 2024
Monday–Friday, March 4–8, 2024; Minneapolis & Virtual
Session S20: Advanced Characterization and Theory
8:00 AM–10:36 AM,
Thursday, March 7, 2024
Room: M101ABC
Sponsoring
Unit:
DCMP
Chair: Zac Ward
Abstract: S20.00013 : Kinetics of hydrogen and vacancy diffusion in iron: A Kinetic Activation Relaxation technique (k-ART) study*
10:24 AM–10:36 AM
Presenter:
aynour khosravi
(Universite de Montreal)
Authors:
aynour khosravi
(Universite de Montreal)
Normand Mousseau
(Universite de Montreal)
Jun Song
(Mcgill University)
Here, we use the kinetic Activation-Relaxation-Technique (k-ART), an off-lattice kinetic Monte Carlo approach with on-the-fly event catalogue building, to help us address the challenging problem in this subject area. Simulations using k-ART are able to provide migration barriers and collective diffusivities of H on microstructures without bias, including elastic effects both at short and long ranges. An ab initio ARTn calculation is used as well to confirm the validity of the results.
More specifically, we investigate hydrogen (H) and mono and divacancy-hydrogen complexes (VHx and V2Hx ) diffusion in BCC iron using k-ART to explore diffusion barriers and associated mechanisms for these defects. We uncover complex diffusion pathways for the bound complexes, with important barrier variations that depend on the geometrical relations between the position of the inserting Fe atom and that of the bound H. Since H is small and brings little lattice deformation around itself, these bound complexes are compact and H is fully unbound at the second neighbor site already. As more H are added, however, vacancies deform and affect the lattice over longer distances, contributing to increasing the VHx complex diffusion barrier and its impact on its local environment. We find that the importance of this trapping decreases when going from mono to divacancy complexes, although diffusion barriers for these complexes increase with the number of trapped H.
*This work is supported in part by a grant from the NSERC. Grateful to Calcul Québec and Compute Canada for providing computer resources. This study was facilitated by the powerful OVITO software.
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