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First-principles investigation of oxygen diffusion mechanism in alpha-titanium crystals

TitleFirst-principles investigation of oxygen diffusion mechanism in alpha-titanium crystals
Publication TypeJournal Article
Year of Publication2017
AuthorsYang, L, Wang, CZ, Lin, SW, Cao, Y
JournalActa Physica Sinica
Date Published06
Type of ArticleArticle
ISBN Number1000-3290
Accession NumberWOS:000403091100028
Keywordsalloy, diffusion, First-principles, high-temperature, Microstructure, oxidation, physics, strain, surface, titanium

frequency nu* is determined from [GRAPHICS] where v(i) and v(j) are the vibration frequency of oxygen atom at the initial state and the transition state respectively. This analysis leads to the formula for calculating the temperature dependent diffusion coefficient by using the microscopic parameters (v(i) and Delta E) from first-principles calculations [GRAPHICS] without any fitting parameters. Using the above formula and the vibration frequencies and diffusion barriers from first-principles calculations, we calculate the diffusion coefficients among different interstitial sites. It is found that the diffusion coefficient from the octahedral center site to the available site nearby is in good agreement with the experimental result, i.e., the diffusion rate D is 1.0465 x 10 (6) m(2).s (1) with Delta E of 0.5310 eV. The jump from the crowdion site to the octahedral interstitial site prevails over all the other jumps, as a result of its low energy barrier and thus leading to markedly higher diffusivity values. The diffusion of oxygen atoms is mainly controlled by the jump occurring between OC and CR sites, resulting in high diffusion anisotropy. This finding of oxygen diffusion behavior in Ti provides a useful insight into the kinetics at initial stage of oxidation in Ti which is very relevant to many technological applications of Ti-based materials.

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