UNITED TECHNOLOGIES RESEARCH CENTER EAST HARTFORD CONN
The oxidationcorrosion characteristics of directionally solidified eutectics including gamma prime-gamma plus alpha alloys are sufficiently well documented to state that oxidation and hot corrosion resistant coatings will be required over a wide range of temperatures. The specific problem with respect to coating the gammagamma-alpha family of alloys is not simply coating chemistry. Rather the major obstacle here involves mating the anisotropic thermal expansion behavior of the substrate with that of the coating so that the latter will not crack under thermal cycling. The approach taken in this study includes minimizing the differences in thermal expansion between the protective coating and the eutectic substrate by selective alloying of the coating and increasing the strain capacity of the coating.