An atomistic view on Oxygen, antisites and vacancies in the γ-TiAl phase

V.I. Razumovskiy, Werner Ecker, David Wimler, Franz-Dieter Fischer, Fritz Appel, Svea Mayer, Helmut Clemens

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The ordered intermetallic γ-TiAl phase plays an important role in determining mechanical properties of engineering γ-TiAl based alloys. During alloy production, interstitial O is introduced in these alloys and in the γ-phase in particular. It is anticipated that it can have a significant impact on mechanical properties of the alloys due to localized dislocation pinning at O atoms and other point defects. In this paper, we apply a standard thermodynamic approach concerning point-defects in ordered compounds together with density functional theory and finite element method calculations to investigate the impact of O on thermal point defect formation and the associated defect formation eigenstrains in the practically relevant Ti-rich off-stoichiometric γ-TiAl phase. The results show that O is strongly bound to vacancies and Ti antisite defects and may substantially increase their equilibrium concentration. Calculated concentrations and eigenstrain values of antisites and vacancies in the presence of O offer a possibility of their interaction with dislocations, promoting dislocations pinning within the strain aging temperature regime of TiAl alloys.

Original languageEnglish
Article number110655
Number of pages8
JournalComputational materials science
Issue numberSeptember
Publication statusPublished - Sept 2021

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