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Vol.41, No.10, 688 ~ 695, 2003
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| Title |
| Evaluation of Long-term Oxidation Properties of Al-21Ti-23Cr and Al-37Ti-12Cr Coating Materials for TiAl Alloy |
| 이재경 Lee Jae Gyeong , 김수현 Kim Su Hyeon , 오명훈 O Myeong Hun , 위당문 Wi Dang Mun |
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| Abstract |
| Both Al-21Ti-23Cr(L1₂+Cr₂Al) and Al-37Ti-12Cr(γ+TiAlCr) two-phase alloys have been accepted to be the most pertinent coating materials in Al-Ti-Cr alloy system to improve the high-temperature oxidation resistance of TiAl alloy taking into consideration of the oxidation properties, the resistance to thermal stress and the chemical compatibility. The cyclic oxidation tests at 1000℃ and 1200℃ were performed for the specimens coated with both materials of 10 mm thickness, and the breakaway oxidation could be observed although both bulk alloys could form a stable Al₂O₃layer. And it was resulted from depleted Al content in the coating layer due to Al₂O₃oxide growth and interdiffusion with substrate. Considering the decrease of Al content resulting from oxide growth, the Al-21Ti-23Cr coating with higher initial Al content was more effective for oxidation protection of TiAl alloy for long-term service. On the other hand, when the change of Al content due to the interdiffusion with substrate was considered, the Al-37Ti-12Cr coating with smaller compositional gradient with TiAl substrate was more effective than the Al-21Ti-23Cr coating. However, it was confirmed through the cyclic oxidation tests at 1000℃ and 1200℃ that the initial Al content was more important for longer life-time of coating materials than the smaller compositional gradient with substrate. Therefore, the Al-21Ti-23Cr coating would be supposed to be more effective for long-term oxidation resistance of TiAl alloys. |
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| Key Words |
| L12-based Al-21Ti-23Cr, γ-based Al-37Ti-12Cr, Long-term oxidation, Interface reaction, Coating materials |
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