Element diffusion during fabrication of EB-PVD NiAl coating and its 1100 °C isothermal oxidation behavior (II)

A two-layer NiAl coating can be deposited by electron beam physical vapour deposition (EB-PVD) on Ni-based superalloy, and the isothermal oxidation test at 1100 °C in air was conducted to evaluate the oxidation behavior of the coating. The dominant phase changed from β-phase to γ′-phase with the oxidation going on. Oxide ridges can be detected on the surface of the as-processed coating, oxide scales on the coating surface can be divided into two categories including the primary scales and the secondary scales formed only after the spallation of the primary scales. The primary scales form to connect the isolated oxide ridges, while the secondary scaleʹs peak clipping effect may cause the surface morphology more and more even.