Effect of Hf, Y and C in the underlying superalloy on the rumpling of diffusion aluminide coatings

摘要: Abstract One form of degradation platinum-modified nickel-aluminide (NiPtAl) coatings on single-crystal superalloys at high temperatures involves a surface instability known as rumpling. In this work, the evolution rumpling during isothermal and cyclic oxidation 1150 °C NiPtAl aluminide coating deposited five different modifications commercial second generation CMSX-4 superalloy is characterized function time. The sensitive to Hf C content underlying superalloy, being largest for alloy containing low hafnium carbon concentrations smallest low-carbon, high-hafnium alloy. It argued that decreases propensity when it diffuses into growing aluminum oxide increasing their creep resistance. An increase in has opposite effect due formation tantalum-rich mixed carbides, which tie up hafnium, thereby decreasing its amount available diffuse oxide. yttrium additions minor.