In situ X-ray tomography investigation of the crack formation in an intermetallic beta-stabilized TiAl-alloy during a stepwise tensile loading
| Autor: | Ch. Löffl, Matthias Göken, Holger Saage |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Mechanical Engineering Alloy Intermetallic 02 engineering and technology engineering.material 021001 nanoscience & nanotechnology Microstructure Industrial and Manufacturing Engineering 020303 mechanical engineering & transports Fracture toughness 0203 mechanical engineering Mechanics of Materials Modeling and Simulation mental disorders Ultimate tensile strength engineering General Materials Science Composite material 0210 nano-technology Embrittlement Tensile testing Stress concentration |
| Zdroj: | International Journal of Fatigue. 124:138-148 |
| ISSN: | 0142-1123 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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