TiAl 합금의 코팅재료로서 Al-Ti-Cr 2상합금의 장시간 산화특성

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. In this study, the analysis on thermal stress through a thermal expansion coefficient, a tensile and compressive test and reaction properties with TiAl alloy by means of bonding coating materials and TiAl substrate was performed. This elucidates the long-term oxidation properties in L1₂-based and γ-based alloys. The difference from a short-term oxidation resistance between L1₂-based alloy and the γ-based alloy was not observed because both alloys could form a stable Al₂O₃ layer. However, although both alloys show similar resistance to thermal stress, it was confirmed that the L1₂-based two-phase alloy has much better oxidation resistance than γ-based two-phase alloy in a long-term oxidation behavior considering the interface reaction properties with TiAl alloy.