In situ X-ray tomography investigation of the crack formation in an intermetallic beta-stabilized TiAl-alloy during a stepwise tensile loading

Journal article


Publication Details

Author(s): Löffl C, Saage H, Göken M
Journal: International Journal of Fatigue
Publication year: 2019
Volume: 124
Pages range: 138-148
ISSN: 0142-1123


Abstract

The impact of high temperature exposure on the mechanical damage behavior of the intermetallic TiAl alloy TNM has been investigated by means of high resolution laboratory computer tomography (CT). An in situ testing device was adapted allowing the study of cracking behavior during tensile testing of unnotched samples by CT. Accordingly, failure of exposed and unexposed samples is controlled by the fracture toughness. Unexposed samples reveal crack formation in the interior at only about 1/3 of their plastic elongation to failure. These internal cracks grow gradually with increasing nominal stress and are subjected to significant crack deflection by the microstructure until the crack growth accelerates and the samples fail. After exposure for 1 h at 800 °C cracks originate in the surface region of the samples at almost the same nominal stresses at which internal cracks first appear. However, due to higher fracture mechanical geometry factor, surface cracks become critical almost instantly after their formation resulting in a reduced ductility, which is known as environmental embrittlement in literature. It is supposed that crack formation at the surface after exposure is the result of stress concentrations which are built-up during plastic deformation due to interstitials in the surface layer.


FAU Authors / FAU Editors

Göken, Mathias Prof. Dr.
Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)


External institutions with authors

Hochschule für angewandte Wissenschaften Landshut


How to cite

APA:
Löffl, C., Saage, H., & Göken, M. (2019). In situ X-ray tomography investigation of the crack formation in an intermetallic beta-stabilized TiAl-alloy during a stepwise tensile loading. International Journal of Fatigue, 124, 138-148. https://dx.doi.org/10.1016/j.ijfatigue.2019.02.035

MLA:
Löffl, Ch, H. Saage, and Mathias Göken. "In situ X-ray tomography investigation of the crack formation in an intermetallic beta-stabilized TiAl-alloy during a stepwise tensile loading." International Journal of Fatigue 124 (2019): 138-148.

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Last updated on 2019-17-05 at 20:08