Journal article
Local deformation at micro-notches and crack initiation in an intermetallic γ-TiAl-alloy
Publication Details
Authors: | Bode, B.; Wessel, W.; Brückner-Foit, A.; Mildner, J.; Wollenhaupt, M.; Baumert, T. |
Publication year: | 2016 |
Journal: | Fatigue and Fracture of Engineering Materials and Structures |
Pages range : | 227-237 |
Volume number: | 39 |
ISSN: | 8756-758X |
DOI-Link der Erstveröffentlichung: |
URN / URL: |
Abstract
The relation is studied between crack initiation from micro-notches in a fully lamellar intermetallic gamma-TiAl alloy and the local strain field. These micro-notches were introduced using femtosecond-laser ablation and had dimensions below the average colony size. The specimen under investigation was then subjected to fatigue loading. Continuous monitoring using a travelling optical microscope allowed detecting microcracks at an early stage. Prior to fatigue loading, a sustained load was applied and the local strain field was determined using digital image correlation. This was supplemented by a Finite Element analysis of the notches and their neighbourhood. It was found that a crack was initiated from a notch causing high normal strains in lamella direction, whereas no crack was initiated from notches with high shear strains.
The relation is studied between crack initiation from micro-notches in a fully lamellar intermetallic gamma-TiAl alloy and the local strain field. These micro-notches were introduced using femtosecond-laser ablation and had dimensions below the average colony size. The specimen under investigation was then subjected to fatigue loading. Continuous monitoring using a travelling optical microscope allowed detecting microcracks at an early stage. Prior to fatigue loading, a sustained load was applied and the local strain field was determined using digital image correlation. This was supplemented by a Finite Element analysis of the notches and their neighbourhood. It was found that a crack was initiated from a notch causing high normal strains in lamella direction, whereas no crack was initiated from notches with high shear strains.
Keywords
crack initiation, intermetallic compounds, physical mesomechanics, small notches, strain localization
