Nanomechanical Characterization of High-Velocity Oxygen-Fuel NiCoCrAlYCe Coating

Abstract

MCrAlY (M = Ni or/and Co) coatings have played an indispensable role in the high-temperature protection system for key components of aero-engines due to their excellent high-temperature oxidation and hot corrosion resistance. Nanoindentation is a useful and highly efficient method for characterizing the nanomechanical properties of materials. The rich information reflecting materials can be gained by load-displacement curves. In addition to common parameters such as elastic modulus and nanohardness, the indentation work and creep property at room temperature can also be extracted. Herein, nanomechanical properties of NiCoCrAlYCe coatings using high-velocity oxygen-fuel (HVOF) spraying were investigated systematically by nanoindentation. The microstructure of as-sprayed NiCoCrAlYCe coatings present mono-modal distribution. Results of nanoindentation reveal that the elastic modulus and nanohardness of NiCoCrAlYCe coatings are 121.08 ± 10.04 GPa and 6.09 ± 0.86 Gpa, respectively. Furthermore, the indentation work of coatings was also characterized. The elastic indentation work is 10.322 ± 0.721 nJ, and the plastic indentation work is 22.665 ± 1.702 nJ. The ratio of the plastic work to the total work of deformation during indentation is 0.687 ± 0.024, which can predict excellent wear resistance for NiCoCrAlYCe coatings. Meanwhile, the strain rate sensitivity determined by nanoindentation is 0.007 ± 0.001 at room temperature. These results can provide prediction of erosion resistance for MCrAlY coatings.