Article as a single crystal of a nickel-based superalloy having a resistance to oxidation improved

摘要

The additions of minor amounts of hafnium and silicon and mixtures thereof to nickel base superalloy single crystal articles provide significantly improved oxidation resistance. The oxidation resistance is improved both for the case of uncoated articles and in the case where a protective coating such as for example, a MCrAlY coating is present. For example the addition of 0.1% hafnium is observed to improve the oxidation resistance by a factor of 4 at 1149 DEG C and a similar addition improved the coated oxidation resistance by a factor of about 2.5 at 1177 DEG C. The preferred single-crystal alloy composition lies within the range:- IMAGE