Cyclic oxidation and interdiffusion behavior of Pt modified NiAlHfCrSi coatings on single crystal superalloy containing Mo

β-NiAlHfCrSi coatings were deposited on a Mo-containing single crystal (SC) superalloy with or without an electro-plated Pt film by electron beam physical vapor deposition (EB-PVD), respectively. Co-doping of Cr and Si caused grain refinement of the coatings and retarded outward diffusion of Pt during heat-treatment in vacuum at 1050 °C. During cyclic oxidation at 1150 °C, severe scale spallation occurred in the Pt-free coating due to the formation of voids beneath the oxide scale. The Pt modified coating effectively suppressed the formation and growth of voids and exhibited improved cyclic-oxidation resistance. Si-doping not only reduced the oxidation rate of the coating but also enhanced the oxide scale adherence, one of mechanisms for which is that the addition of Si in the coating prevented outward diffusion of refractory elements such as Mo from the alloy substrate.