Original title:
High Temperature Fatigue Behaviour of Third Generation of TiAl Alloys
Authors:
Obrtlík, Karel ; Kruml, Tomáš Document type: Papers Conference/Event: International Colloquim Mechanical Fatigue of Materials - ICMFM /16./, Brno (CZ), 2012-09-24 / 2012-09-26
Year:
2012
Language:
eng Abstract:
Low cycle fatigue properties of lamellar TiAl with 7.8 at.% Nb were studied at four temperatures: room temperature, 700, 750 and 800 °C. Up to 750 °C, stable cyclic behaviour is observed while cyclic softening is characteristic for 800°C. The strength of the alloy is still high even at 800 °C. The TEM observation did not reveal any substantial changes in the microstructure due to the cycling at RT. At 750 °C, the lamellar structure was in some places destroyed by cyclic plasticity and pure g-phase islands with high density of dislocation debris were formed. At 800 °C, the domains without lamellar structure cover about 10% of inspected volume and are almost dislocation free. The results show that the diffusion processes leading to vanishing of small prizmatic dislocation loops start to operate between 750 and 800 °C. The destruction of lamellar microstructure and annealing of dislocation debris is the reason for cyclic softening at 800 °C.
Keywords:
high temperature fatigue; lamellar microstructure; TEM; TiAl Project no.: ED1.1.00/02.0068, GAP107/11/0704 (CEP) Funding provider: GA MŠk, GA ČR Host item entry: Proceedings of the 16th International Colloquium Mechanical Fatigue of Materials, ISBN 978-80-87434-05-5
Institution: Institute of Physics of Materials AS ČR
(web)
Document availability information: Fulltext is available at the institute of the Academy of Sciences. Original record: http://hdl.handle.net/11104/0216786