TY - JOUR

T1 - An atomistic view on Oxygen, antisites and vacancies in the γ-TiAl phase

AU - Razumovskiy, V.I.

AU - Ecker, Werner

AU - Wimler, David

AU - Fischer, Franz-Dieter

AU - Appel, Fritz

AU - Mayer, Svea

AU - Clemens, Helmut

N1 - Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/9

Y1 - 2021/9

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85108361791&partnerID=8YFLogxK

U2 - 10.1016/j.commatsci.2021.110655

DO - 10.1016/j.commatsci.2021.110655

M3 - Article

VL - 197.2021

JO - Computational materials science

JF - Computational materials science

SN - 0927-0256

IS - September

M1 - 110655

ER -