Diffusion of oxygen in bcc Fe under the influence of other foreign atoms


Diffusion of oxygen in bcc Fe under the influence of other foreign atoms

Wang, X.; Posselt, M.; Faßbender, J.

First-principle calculations and kinetic Monte Carlo simulations are applied to investigate the diffusion of oxygen in bcc Fe under the influence of other foreign atoms, such as Al, Si, P, S, Ti,, Cr, Mn, Ni, Y, and Mo. In the first part of this work jumps of oxygen in pure bcc Fe, between first-, second-, and third-neighbor octahedral interstitial sites were investigated by DFT. It is found that a second-neighbor jump consists of two consecutive first-neighbor jumps and that the barrier of the third-neighbor jump is too high to be relevant. In the second part DFT was applied to determine the modified migration barriers, i.e. for the oxygen jump between the first and the second neighbor of a foreign atom, etc. It is found that Si, P, Ni and Mo influence the migration barriers of oxygen only slightly. Al and Cr cause moderate changes, while S, Ti, and Y lead to strong modifications. With the exception of Y the migration paths are first-neighbor jumps between (modified) octahedral sites with (modified) tetrahedral sites as saddle points. Y changes some migration paths considerably. Using the migration barriers calculated by DFT the diffusion coefficient of oxygen was determined by kinetic Monte Carlo simulations considering a dilute iron alloy. In general the foreign atoms cause a reduction of the mobility of oxygen compared to that in pure bcc Fe. The strongest decrease is obtained for the foreign atoms S, Ti, and Y.

Keywords: Diffusion; oxygen; bcc Fe; Density Functional Theory; Kinetic Monte Carlo simulations

  • Poster
    DPG-Frühjahrstagung und EPS-CMD27, 11.-16.03.2018, Berlin, Deutschland

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Publ.-Id: 27225