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Fatigue Failure Analyses on a Ti-45Al-8Nb-0.2W-0.2B-0.1Y Alloy at Different Temperatures
Department of Engineering Mechanics, AML, Tsinghua University, Beijing 100084, China
State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
Division of International Exchange Support, Center for Globalization, Kumamoto University, Kumamoto 860-8555, Japan
Department of Mechanical System Engineering, Daiichi Institute of Technology, Kagoshima 899-4395, Japan
* Author to whom correspondence should be addressed.
Received: 27 August 2012; in revised form: 28 October 2012 / Accepted: 1 November 2012 / Published: 9 November 2012
Abstract: The fatigue micro crack initiation and propagation tests of a TiAl alloy with 8% Nb content were carried out by using scanning electron microscopy in situ technology at room temperature and at 750 °C. These results indicated that the fatigue micro crack initiation was mainly caused by the stress concentration at room temperature, but at an elevated temperature (750 °C) the multi-cracks were caused by the coupled factors of both lamellar microstructure and stress concentration. Therefore, fatigue micro crack initiation behavior is much more dependent on the lamellar structure at an elevated temperature. One of the reasons is that the elevated temperature degrades the interface strength between the lamellar of the TiAl alloy with 8% Nb content. Therefore, the small fatigue crack propagation behavior of the alloy exhibited a mixture damage model of interlamellar and translamellar at a micro scale. The crack growth path and fracture characteristics provided a proof of crack deflection, branching and/or bridging induced either by interlamellar or by translamellar failure mode.
Keywords: titanium aluminum; fatigue crack; microstructure; in situ SEM test
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Wang, X.-S.; Zhang, M.; Song, X.-P.; Jia, S.; Chen, Q.; Kawagoishi, N. Fatigue Failure Analyses on a Ti-45Al-8Nb-0.2W-0.2B-0.1Y Alloy at Different Temperatures. Materials 2012, 5, 2280-2291.
Wang X-S, Zhang M, Song X-P, Jia S, Chen Q, Kawagoishi N. Fatigue Failure Analyses on a Ti-45Al-8Nb-0.2W-0.2B-0.1Y Alloy at Different Temperatures. Materials. 2012; 5(11):2280-2291.
Wang, Xi-Shu; Zhang, Min; Song, Xi-Ping; Jia, Su; Chen, Qiang; Kawagoishi, Norio. 2012. "Fatigue Failure Analyses on a Ti-45Al-8Nb-0.2W-0.2B-0.1Y Alloy at Different Temperatures." Materials 5, no. 11: 2280-2291.