The scaling behavior of sputtered Ni3Al coatings with and without Pt modification

A Ni3Al nanocrystalline film was deposited on the Ni3Al-based superalloy IC6 by magnetron sputtering. Pt-modified coatings were obtained by electroplating 1.5 μm platinum onto the sputtered Ni3Al film with and without annealing. Duplex scale developed on the sputtered Ni3Al film after 20 h isothermal exposure at 1050 °C. Uphill diffusion of Al occurred in the Pt-modified coating system, which implied that inward diffusion of Al from coating to substrate was prevented. Platinum promoted selective oxidation of Al, although 5 at.% Pt was insufficient for the development of exclusive alumina scale on the Pt-modified sputtered γ′-Ni3Al coating.

► A Pt layer on sputtered Ni3Al film led to formation of exclusive alumina scale.
► Incorporation of Pt in sputtered Ni3Al coating resulted in uphill diffusion of Al.
► Incorporation of Pt in sputtered Ni3Al coating promoted selective oxidation of Al.