Oxidation behavior and mechanical properties of yttrium-doped L1{sub 2}(Al,Cr){sub 3}Ti coating on TiAl alloys

Journal Article · Fri Oct 22 04:00:00 EDT 1999 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(99)00260-2· OSTI ID:20001707

Lee, H N; Park, Z M; Oh, M H; Kim, K Y; Wee, D M

Gamma-based TiAl has great potential for application in aircraft engines, due to its low density, high specific strength and excellent high-temperature properties compared to currently used nickel-base superalloys. However, the poor oxidation resistance limits the use of TiAl above 1,073 K because the external layer formed on these compounds is not a protective Al{sub 2}O{sub 3} scale, but rather TiO{sub 2}, or a mixture of Al{sub 2}O{sub 3} and TiO{sub 2}. Recently, however, some promising results were found in the Ti-Al-Cr system. Meier et al. found that Ti-Al-Cr alloys containing a minimum of 8--10 at.% chromium are continuous Al{sub 2}O{sub 3} scale formers up to 1,573 K in air. Furthermore, Brady et al. suggested that the alloy composed of {gamma}-phase and Laves phase in the Ti-Al-Cr system is a prospective coating material for TiAl. Moreover, in their previous work, the authors reported that Al-21Ti-23Cr (at.%) coating was very effective in decreasing the oxidation rate of Ti-48Al compared to the CoCrAl and the CoCrAlY coatings. However, mass gain of the coated specimen increased rapidly after 100 cycles during cyclic oxidation. In this study, in order to improve the oxidation resistance of Al-21Ti-23Cr coating by yttrium additions, reasonably yttrium addition content was determined by isothermal oxidation tests and scratch tests. Also, the oxidation behavior of the coated specimen was examined through a cyclic oxidation test, and the tensile and creep properties of uncoated and coated specimens were investigated.

• Research Organization: KAIST, Taejon (KR)
• OSTI ID: 20001707
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 10 Vol. 41; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
CREEP
INTERMETALLIC COMPOUNDS
OXIDATION
PROTECTIVE COATINGS
SCALING
TENSILE PROPERTIES
TITANIUM ALLOYS
YTTRIUM ADDITIONS