Effect of Cr addition on the properties of aluminide coating layers formed on TiAl alloys

TiAl alloys were coated by two different processes with a simple aluminide coating and a Cr+Al-type composite coating for the improvement of oxidation resistance of the alloy. Simple aluminizing was applied to TiAl– XCr ( X=1, 4, 6 at.%) alloys. A Cr+Al-type composite coating was performed by Cr eva...

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Bibliographic Details
Published in:Surface & coatings technology 2002-05, Vol.154 (1), p.75-81
Main Authors: Gyo Jung, Hwan, Ju Jung, Dong, Kim, Kyoo Young
Format: Article
Language:English
Subjects:
Alumininide coating
Applied sciences
Cr evaporation
Ductility
Exact sciences and technology
Grain refinement
L1 2-Ti(Al,Cr) 3
Metallic coatings
Metals. Metallurgy
Production techniques
Surface treatment
TiAl alloys
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Summary:TiAl alloys were coated by two different processes with a simple aluminide coating and a Cr+Al-type composite coating for the improvement of oxidation resistance of the alloy. Simple aluminizing was applied to TiAl– XCr ( X=1, 4, 6 at.%) alloys. A Cr+Al-type composite coating was performed by Cr evaporation on the TiAl substrate followed by pack aluminizing. A simple aluminide coating applied to the Cr-added TiAl alloys showed improvement of ductility and oxidation resistance. This was mainly due to grain refinement of the Cr-added coating layer. The coating layer formed by the composite coating process consisted of the Al 4Cr outer layer and TiAl 3 inner layer. However, these coating layers were transformed to a Ti(Al,Cr) 3 layer with a L1 2 structure during oxidation. This layer showed much better ductility compared to other coating layers and superior oxidation resistance in cyclic oxidation tests.
ISSN:0257-8972
1879-3347
DOI:10.1016/S0257-8972(01)01716-9