Cross-sectional oxide distribution of cast IN738 and its sputtered coating at 1000 °C

A sputtered nanocrystalline coating of IN738 alloy was obtained by means of magnetron sputtering technique. The oxide distribution was presented of the cast IN738 and its coating after 50 h in air at 1000 °C. The results indicated that the oxide scale formed on the cast alloy consisted roughly of three sections: the top-most section being Cr2O3 and TiO2 mixture, followed by internal aluminum oxide, and scattering beneath which being TiN particles. In the case of nanocrystalline coating, however, only two sections were obvious: the top Cr2O3, TiO2 and NiCr2O4 spinel mixture layer and the inner continuous Al2O3 layer. No internal oxidation and nitridation occurred.