An atomistic view on Oxygen, antisites and vacancies in the γ-TiAl phase
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In: Computational materials science, Vol. 197.2021, No. September, 110655, 09.2021.
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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 -