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Ferrari, A. |
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Schimpf, Christian |
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Dunser, M. |
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Thomas, Eric |
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Gecse, Zoltan |
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Tsrunchev, Peter |
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Della Ricca, Giuseppe |
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Cios, Grzegorz |
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Hohlmann, Marcus |
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Dudarev, A. |
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Mascagna, V. |
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Santimaria, Marco |
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Poudyal, Nabin |
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Piozzi, Antonella |
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Mørtsell, Eva Anne |
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Jin, S. |
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Noel, Cédric |
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Fino, Paolo |
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Mailley, Pascal |
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Meyer, Ernst |
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Zhang, Qi |
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Pfattner, Raphael | Brussels |
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Kooi, Bart J. |
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Babuji, Adara |
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Pauporte, Thierry |
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Clemens, H.
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Topics
Publications (9/9 displayed)
- 2021On the Formation Mechanism of Banded Microstructures in Electron Beam Melted Ti–48Al–2Cr–2Nb and the Design of Heat Treatments as Remedial Actioncitations
- 2021Designing advanced intermetallic titanium aluminide alloys for additive manufacturingcitations
- 2018Non-equilibrium solid solution of molybdenum and sodium: Atomic scale experimental and first principles studiescitations
- 2013An in-situ high-energy X-ray diffraction study on the hot-deformation behavior of a β-phase containing TiAl alloy
- 2012In Situ Study of Gamma-TiAl Lamellae Formation in Supersaturated alpha(2)-Ti 3 Al Grains
- 2012In-situ synchrotron study of B19 phase formation in an intermetallic $%5Cgamma$-TiAl alloycitations
- 2011Deformation mechanisms in micron-sized PST TiAl compression samples: Experiment and modelcitations
- 2010Can local hot spots induce α 2 /γ lamellae during incomplete massive transformation of γ-TiAl alloys?citations
- 2006Characterization of the behavior under impact loading of a maraging steel strengthened by nano-precipitates
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article
Deformation mechanisms in micron-sized PST TiAl compression samples: Experiment and model
Abstract
Titanium aluminides are the most promising intermetallics for use in aerospace and automotive applications. Consequently, it is of fundamental interest to explore the deformation mechanisms occurring in this class of materials. One model material which is extensively used for such studies are polysynthetically twinned (PST) TiAl crystals, which consist predominantly of parallel γ-TiAl and, fewer, α2-Ti3Al lamellae. In the present study, PST TiAl crystals with a nominal composition of Ti–50 at.% Al were machined by means of the focused ion beam (FIB) technique into miniaturized compression samples with a square cross-section of approximately 9 µm x 9 µm. Compression tests on the miniaturized samples were performed in situ inside a scanning electron microscope using a microindenter equipped with a diamond flat punch. After deformation, thin foils were cut from the micro-compression samples and thinned to electron transparency using a FIB machine in order to study the deformation structure by transmission electron microscopy (TEM). The TEM studies reveal mechanical twinning as the main deformation mechanism at strains of 5.4%, while at strains of 8.3% dislocation glide becomes increasingly important. The experimentally observed twins scale in size with the width of the γ-TiAl lamella. A kinematic and thermodynamic model is developed to describe the twin-related length change of the micro-compression sample at small strains as well as the relationship of an increase of twin width with increasing γ-TiAl lamella thickness. The developed twin model predicts a width of the twins in the range of a few nanometers, which is in agreement with experimental findings.