Influence of surface modification and long-term exposure on mechanical creep properties of γ-TiAl G4

An investigation of the corrosion processes were performed for coated and uncoated γ-TiAl G4, an alloy designed to work in the temperature range 750 - 800°C, where oxidation and corrosion phenomena occur. An aluminising pack cementation treatment was used to improve the oxidation resistance of this...

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Bibliographic Details
Published in:Materials at high temperatures 2009-12, Vol.26 (4), p.339-346
Main Authors: Bacos, Marie-Pierre, Thomas, Marc, Raviart, Jean-Louis, Morel, Ariel, Navéos, Serge, Josso, Pierre
Format: Article
Language:English
Subjects:
aluminisation
corrosion
creep
microstructure
oxidation
titanium aluminide
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Summary:An investigation of the corrosion processes were performed for coated and uncoated γ-TiAl G4, an alloy designed to work in the temperature range 750 - 800°C, where oxidation and corrosion phenomena occur. An aluminising pack cementation treatment was used to improve the oxidation resistance of this γ-TiAl G4 alloy. Cyclic corrosion tests were performed at 800°C in air for up to 800 1-hour cycles with a Na 2 SO 4 /NaCl mixture. The influence of both aluminisation and the corrosion phenomena on the creep behaviour was investigated. The cyclic corrosion resistance of the coated γ- TiAl G4 was shown to be improved by aluminising. The pack cementation treatment had no detrimental effect on the creep behaviour. Moreover, neither is creep affected by the corrosion of coated specimens. As corroded uncoated specimen exhibited good creep behaviour, it can be concluded that this alloy is suitable, even without coating, for turbine applications in hot corrosion atmospheres at least up to 800°C.
ISSN:0960-3409
1878-6413
DOI:10.3184/096034009X12564836188647