Overlay coatings with high yttrium contents

摘要

Improved coating compositions are described for the protection of superalloys at elevated temperatures, particularly where Hf is absent from the substrate alloy. The coatings of the NiCrAlY or NiCoCrAlY type are significantly improved by the use of higher levels of yttrium. The preferred compositions are within the following range Element wt% Cr 10-35 Al 8-20 Y 11-30 Co 0-30 Ni Balance e