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Diffusion of interstitials in metallic systems, illustration of a complex study case: aluminum

David, Matthieu and Connétable, Damien Diffusion of interstitials in metallic systems, illustration of a complex study case: aluminum. (2017) Journal of Physics : Condensed Matter, 29 (45). 1-10. ISSN 0953-8984

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Official URL: http://dx.doi.org/10.1088/1361-648X/aa8e5e

Abstract

While diffusion mechanisms of interstitial elements in fcc systems are generally well-known, especially in the case of H atoms, we show in this work that even in the case of a simple metallic system (aluminum), the diffusion of interstitials exhibits a wide variety of paths and mechanisms that depend on the specie. We used an approach based on first-principles calculations associated with kinetic Monte-Carlo simulations and a multi-state diffusion formalism to compute the diffusion coefficients of five interstitial elements: hydrogen, boron, carbon, nitrogen and oxygen. For instance, at the atomic scale, whilst we find that C atoms prefer to be located in octahedral sites (labeled o) rather than in tetrahedral positions (labeled t), we find one additional stable position in the lattice (M). The diffusion through these three stable positions are thus studied in detail. In the case of B atoms, for which the tetrahedral site is found unstable, the diffusion path is between o-o sites. Similarly, in the case of oxygen, t positions are found to be the only stable positions (o are unstable) and the path of migration, along t-t direction, is found through a twice degenerated asymmetric transition state. In the case of H and N atoms for which t and o sites are stable, we explain why the only path is along the t-o direction. Finally, we discuss explicit formulas to compute coefficients of diffusion of interstitials in fcc structures

Item Type:Article
Additional Information:Thanks to Institute of Physics editor. The original PDF of the article can be found at Journal of Physics : Condensed Matter website : http://iopscience.iop.org/article/10.1088/1361-648X/aa8e5e/meta
HAL Id:hal-01687188
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: cirimat webmestre
Deposited On:18 Jan 2018 10:29

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