Comparison of the oxidation behavior of β and γ-γ′ NiPtAl coatings

This study compared the oxidation behaviors of γ-γ′ NiPtAl coatings and traditional β-phase NiPtAl bond coatings. Both types of NiPtAl coatings were fabricated on two different single-crystal Ni-base superalloys using the same source of electroplated Pt. Characterization of the coating composition and alumina scale morphology after cyclic oxidation in dry oxygen at 1150 °C indicated that the addition of Ti in one superalloy had affected the scale microstructure and had degraded scale adhesion on the γ-γ′ coating. In general, the alumina scale formed was thicker on the γ-γ′-coated substrates, and those coatings contained a larger number of pores, thought likely to be primarily due to a Kirkendall-type effect.