| To improve the oxidation resistance of γ-based TiAl alloy, Al-Ti-Cr coatings of approximately 150 ㎛ thickness were deposited on Ti-48Al alloy using an air plasma spraying(APS) process. We used Al-Ti-Cr powders with the composition of Al-2lTi-23Cr(at.%). Isothermal and cyclic oxidation tests at 1000℃ in air were utilized to investigate the oxidation resistance of both Al-Ti-Cr coatings and of TiAl alloys with Al-Ti-Cr coatings. Phase identification of Al-Ti-Cr coatings was performed by XRD. After exposure at 1000℃ in air, rutile TiO_2, which resulted from the oxidation of Ti during spraying, was always found in addition to protective α-Al_2O_3 in the oxide scale. However, isothermal and cyclic oxidation tests of a Ti-48Al alloy coated with an Al-Ti-Cr coating showed that this coating improved the oxidation resistance of TiAl alloy at 1000℃ despite partial spalling in the Al-Ti-Cr coating layer. Moreover, cyclic oxidation tests of Al-Ti-Cr coatings showed stable oxidation behavior at 1000℃ up to 100h because of good adhesion between the coating layer and the oxide scale although the growth rate of oxide was relatively high. Therefore, it could be suggested that the Al-Ti-Cr coating was effective in enhancing the oxidation resistance of the TiAl alloy at 1000℃, although the improvement of adhesion between the coating layer and the TiAl substrate was required. |
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