Oxidation resistance of sputtered Ni3(AlCr) nanocrystalline coating

Isothermal and cyclic oxidation resistance at 1000°C in air were investigated for a cast Cr-containing Ni₃Al-base alloy and its sputtered nanocrystalline coating. The results indicated that both the cast Ni₃Al alloy and its sputtered coating exhibit excellent isothermal oxidation resistance as a result of the formation of Al₂O₃ scales. However, the cast alloy possesses very poor cyclic oxidation resistance because of the spallation of the initially formed Al₂O₃ scale during cooling and subsequent formation of NiO. On the contrary, the sputtered Ni₃(AlCr) nanocrystalline coating exhibits very good cyclic oxidation resistance due to the significant improvement of the adhesion of Al₂O₃.