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The Isothermal and Cyclic Oxidation Behavior of a Titanium Aluminide Alloy at Elevated Temperature

  • S.Y. Chang
Article

The isothermal and cyclic oxidation behavior of Ti-47Al-2Mn-2Nb with 0.8 vol.% TiB2 particle-reinforced alloy was investigated in air between 700 and 1000 °C. In the study, the kinetics of isothermal and cyclic oxidation were performed by using a continuous thermogravimetric method which permits mass change measurement under oxidation conditions. The oxide scales and substrates were characterized by scanning electron microscopy with energy-dispersive x-ray analysis and x-ray diffraction. At 700 and 800 °C, the alloy showed an excellent oxidation resistance under isothermal and cyclic conditions. After exposure to air above 800 °C, the outer scale of the alloy was dominated by a fast-growing TiO2 layer. Under the coarse-grained TiO2 layer was the Al2O3-rich scale, which was fine-grained. At 900 and 1000 °C, the extent of oxidation increased clearly. The oxidation rate follows a parabolic law at 700 and 800 °C. However, the alloy, upon isothermal oxidation at 900 °C, can be divided into several stages. During the cyclic oxidation at 900 and 1000 °C, partial scale spallation takes place, leading to a stepwise mass change.

Keywords

cyclic oxidation isothermal oxidation oxidation kinetics thermogravimetric analysis TiAl-based intermetallic 

Notes

Acknowledgment

Special thanks go to National Science Council (under Grant# NSC94-2216-E-010-CC3) for their sponsorship of this research project.

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Copyright information

© ASM International 2007

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringNational Yunlin University of Science & TechnologyTouliuTaiwan

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