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First-principles study of diffusion and interactions of vacancies and hydrogen in hcp-titanium

Connétable, Damien and Huez, Julitte and Andrieu, Eric and Mijoule, Claude First-principles study of diffusion and interactions of vacancies and hydrogen in hcp-titanium. (2011) Journal of Physics : Condensed Matter, vol. 23 (n° 40). pp. 405401 (1) - 405401 (14). ISSN 0953-8984

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Official URL: http://dx.doi.org/10.1088/0953-8984/23/40/405401

Abstract

We present a study of the stability of n-vacancies (Vn) and hydrogens in the hexagonal close-packed titanium system computed by means of first-principles calculations. In this work, performed by using the generalized gradient approximation of density functional theory, we focused on the formation energies and the processes of migration of these defects. In the first part, the calculated formation energy of the monovacancy presents a disagreement with experimental data, as already mentioned in the literature. The activation energy is underestimated by almost 20%. The stability of compact divacancies was then studied. We show that a divacancy is more stable than a monovacancy if their migration energies are of the same order of magnitude. We also predict that the migration process in the basal plane of the divacancy is controlled by an intermediate state corresponding to a body-centered triangle(BO site). The case of the trivacancies is finally considered from an energetic point of view. In the second part, the insertion of hydrogen and the processes of its migration are discussed. We obtain a satisfactory agreement with experimental measurements. The chemical nature of the interactions between hydrogen and titanium are discussed, and we show that the H-atom presents an anionic behavior in the metal. The trapping energy of hydrogen in a monovacancy as a function of the number of hydrogen atoms is finally presented.

Item Type:Article
Additional Information:Thanks to OIP Publishing editor. The definitive version is available at http://iopscience.iop.org/ The original PDF of the article can be found at Journal of Physics : Condensed Matter website: http://iopscience.iop.org/0953-8984/23/40/405401/
Audience (journal):International peer-reviewed journal
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Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
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Deposited By:Denis Faragou

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