Effect of Ti and Ta on the oxidation of a complex superalloy

The oxidation behaviors of a series of directionally solidified Ni-base superalloys were studied at 1000 and 1100 C. These alloys are based on a composition of Ni-4.2Co-4.8Cr-12.8Al-1.6W3.1Mo-1.0Re (at. %), with additions of Ta and Ti. Both Ta and Ti partition to alloy phases in a manner similar to...

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Bibliographic Details
Published in:Oxidation of metals 1981-06, Vol.15 (5-6), p.375-397
Main Author: Yang, S W
Format: Article
Language:English
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Summary:The oxidation behaviors of a series of directionally solidified Ni-base superalloys were studied at 1000 and 1100 C. These alloys are based on a composition of Ni-4.2Co-4.8Cr-12.8Al-1.6W3.1Mo-1.0Re (at. %), with additions of Ta and Ti. Both Ta and Ti partition to alloy phases in a manner similar to Al. With addition of 1 at. % of Ta, the oxidation resistance is improved significantly, while 1 at. % of Ti appears to have no effect. Raising the concentration of Ta and Ti to 3 at. % degrades the oxidation resistance. The degradation is especially severe with 3 at. % of Ta. At only 1 at. % of Ta and Ti, both alloys establish a protective layer of Al2O3. The loss of the oxidation resistance at 3 at. % addition of Ta and Ti is related to the formation of complex oxides which are less protective. Detailed analysis of the oxide phases are conducted using a combination of X-ray diffraction and SEM. Characterizations of the oxidation behaviors are made under isothermal and cyclic conditions. The discrepancies between data obtained under both conditions were noted.
ISSN:0030-770X
1573-4889
DOI:10.1007/bf00603531