Oxidation behavior of nanocrystalline Pt-γ′ coating with embedded Al2O3 nanoparticles at 1050 °C

Abstract

Nanocrystalline Pt-γ′ coatings (NC Pt-γ′) with embedded Al₂O₃ nanoparticles were fabricated on single-crystal superalloy through reactive magnetron sputtering to explore oxidation behavior of NC Pt-γ′ at 1050 °C. Results indicate that Al₂O₃ scale was formed on surface of the coarse-grain structured Pt-γ′ coating. However, as oxidation time is prolonged, Al content in the coating decreases, and a multi-layered oxide scale is formed on the surface. In contrast, NC Pt-γ′ coating exhibits high oxidation resistance due to a large number of boundaries provided by nanocrystalline structure, which facilitates rapid diffusion of Al. In addition, nano Al₂O₃ particles were precipitated in the coating due to mild addition of O into the coating. The nanoparticles distributed at grain boundaries of the coating can inhibit the growth of grains at high temperature.