Oxidation behavior of sputtered Ni–Cr–Al–Ti nanocrystalline coating

Magnetron sputter deposition was used to prepare Ni–9.7Cr–5.5Al–7Ti (wt%) nanocrystalline coatings on the substrates of the same material. The oxidation behavior of the cast Ni–Cr–Al–Ti alloy and its sputtered coating at 1000°C in air was investigated. An α-Al2O3 scale with TiO2 dispersions was formed on the sputtered coating after 200 h of oxidation; even so good oxidation resistance was exhibited. The formation of TiO2 was attributed to the high ratio of Ti/Al in the coating. The high content of Cr and the precipitation of Ni3(AlTi) in the sputtered coating during oxidation could restrict the formation and growth of TiO2. Therefore, good oxidation resistance was shown by the sputtered Ni–Cr–Al–Ti coating despite the formation of TiO2.