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 o C. The results indicated that the oxide scale formed on the cast alloy consisted roughly of three sections: the top-most section being Cr 2 O 3 and TiO 2 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 Cr 2 O 3 , TiO 2 and NiCr 2 O 4 spinel mixture layer and the inner continuous Al 2 O 3 layer. No internal oxidation and nitridation occurred.