Abstract: The cyclic oxidation resistance of cast Ni-base superalloy K38G and its sputtered micro-grained film were studied between 950℃ and room temper- ature in air.The results show that the weight gain of micrograined films is much less than that of cast al- loy during cyclic oxidation,and the resistance of micro-grained fihns is even better than that of the aluminide coating on the same alloy.On the surface of cast alloy K38G,complex oxide scales of Cr_2O_3, TiO_2 and NiCr_2O_4 spinel formed and they began to spall alter about 30 cycles of test.However,on the micro-grained films,continuous and thin α-Al_2O_2 scale was formed and did not spall throughout the cyclic oxidation test.

Key words: microcrystal sputtering, cyclic oxidation, superalloy