Rumpling of nickel aluminide coatings : a reassessment of respective influence of thermal grown oxide and phase transformations

The respective influence of the oxidation and phase transformation on the rumpling of nickel aluminide coatings is reviewed using the thermal treatments in air and Ar atmosphere: β-(Ni,Pt)Al coating deposited on AM1 Ni-base superalloy was subjected to the isothermal and cyclic oxidation at 1100 °C as well as to the thermal cycling in Ar atmosphere. A comparative study of the coating microstructure evolution and surface roughness increase in different conditions suggests that the presence of adherent oxide layer is essential for the rumpling of nickel aluminide coatings on Ni-base superalloys.