Influence of niobium alloying on the low cycle fatigue of cast TiAl alloys at room and high temperatures

0346327 - ÚFM 2011 RIV NL eng J - Journal Article
Kruml, Tomáš - Petrenec, Martin - Obrtlík, Karel - Polák, Jaroslav - Buček, Petr
Influence of niobium alloying on the low cycle fatigue of cast TiAl alloys at room and high temperatures.
Procedia Engineering. Roč. 2, č. 1 (2010), s. 2297-2305. E-ISSN 1877-7058.
[Fatigue 2010. Praha, 06.06.2010-11.06.2010]
R&D Projects: GA ČR GA106/08/1631; GA ČR GA106/07/0762
Institutional research plan: CEZ:AV0Z20410507
Keywords : Low cycle fatigue * lamellar TiAl alloy * fracture surface
Subject RIV: JL - Materials Fatigue, Friction Mechanics

The low-cycle fatigue properties of TiAl alloys with 2 at.% and 7 at.% of Nb with nearly lamellar microstructure were studied at room temperature and 750 degrees C. Cyclic hardening/softening curves, cyclic stress-strain curves (CSSC) and fatigue life curves were obtained at both temperatures as well as monotonic tensile properties. Both materials show stable cyclic response at 750 degrees C. At room temperature, significant cyclic hardening characteristic for 2 at.% Nb alloy is not observed for 7 at.% Nb alloy. This difference is attributed to higher Nb content which increases the stacking fault energy and thus prevents intensive twinning. Parameters of the CSSC, the Manson-Coffin law and the Basquin law were determined. The cyclic strength of the alloy with 7 at.% Nb is substantially higher in comparison with 2 at.% Nb, probably due to lower thickness of the lamellas.
Permanent Link: http://hdl.handle.net/11104/0187386