Oxidation behavior and mechanism of GH4975 superalloy prepared electron beam smelting between 900 °C and 1100 °C in air

Abstract

In this work, the oxidation behavior and mechanism of GH4975 alloy prepared electron beam smelting were investigated in air at 900–1100 °C. The results show that the oxidation weight gain curve follows a parabolic law, and the oxidation activation energy of GH4975 alloy is 183.465 kJ/mol. The oxide film is mainly composed of NiO in the outer layer, CoCr2O4, TiO2, Cr2O3 and small amount of Al2O3 in the intermediate layer, and Al2O3 in the inner layer. After long-term oxidation, the outward release of internal stresses generated by CoCr2O4 and Cr2O3 will cause flaking of the outer oxide layer and part of the intermediate oxide layer. The formation mechanism and flaking behavior of oxide film were explained, and a growth model and flaking model of oxide film was established, which will provide a reference for the high temperature oxidation behavior of GH4975 alloy.