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A dislocation-scale characterization of the evolution of deformation microstructures around nanoindentation imprints in a TiAl

Abstract : Titanium aluminide (TiAl) alloys have attracted considerable attention due to their unique combination of properties such as high specific strength and stiffness, good creep properties and resistance against oxidation and corrosion, which make them suitable candidate materials for High Temperature (HT) applications [1]. TiAl alloys are brittle at Room Temperature (RT), i.e. below their brittle-to-ductile transition temperature which lies between 800°C and 1000°C [2]. Despite intense research, literature suffers from a lack of understanding of their elementary deformation mechanisms and the precise role of microstructures [2]. The investigation presented here focuses on the study of RT deformation mechanisms at the mesoscopic scale. With an original combination of experiments, we investigate the evolution of deformation microstructures at RT in the γ phase of a dual-phase bulk TiAl alloy. Because of the RT brittleness of this material, plastic deformation is induced by nanoindentation. The evolution of the microstructures is characterized by accurate Electron Channeling Contrast Imaging (aECCI) before and after deformation [3]. aECCI is a non-destructive powerful method offering the ability to provide, inside a SEM, TEM-like diffraction contrast imaging of sub-surface defects (at a depth of about one hundred of nanometers) on centimetric bulk specimen [4]. Defects, such as dislocations, can be characterized by applying the TEM extinction criteria [5]. Accommodation of the deformation are reported and a scenario is proposed [3]. Références [1] – Y. Kim, D. Dimiduk, JOM 43, (1991). [2] – C. Zambaldi, Thèse, Aachen (2010). [3] – A. Guitton, H. Kriaa, E. Bouzy, J. Guyon, N. Maloufi, Materials 11, 2 (2018) [4] – H. Kriaa, A. Guitton, N. Maloufi, Scientific reports 7, (2017). [5] – H. Kriaa, A. Guitton, N. Maloufi, Materials 12 (2019)
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https://hal.univ-lorraine.fr/hal-03043111
Contributor : Antoine Guitton <>
Submitted on : Monday, December 7, 2020 - 10:20:03 AM
Last modification on : Friday, February 26, 2021 - 2:48:03 PM

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  • HAL Id : hal-03043111, version 1

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Antoine Guitton, Hana Kriaa, Emmanuel Bouzy, Julien Guyon, Nabila Maloufi. A dislocation-scale characterization of the evolution of deformation microstructures around nanoindentation imprints in a TiAl. Plasticité, 2018, Nancy, France. ⟨hal-03043111⟩

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