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

Abstract

<p>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.</p>

Topics

• density
• impedance spectroscopy
• compound
• phase
• theory
• Oxygen
• dislocation
• density functional theory
• aging
• intermetallic
• interstitial
• aging
• point defect