Oxidation behavior of GTD111 Ni-based superalloy at 900°C in air

The oxidation behavior of GTD111 Ni-based superalloy was investigated at 900°C from 1h to 452h. The detailed oxide structure, from the top surface down to the base material, was clarified by modelling studies as Ni–Ti oxides, Cr–Ti oxides, Cr2O3 oxide band, Ni–W–Ta oxide and finally a blocky Al2O3 region. Internal oxide Al2O3 was discontinuous, Cr2O3 oxide dense band provided the most protection against further oxidation. Cracking and spalling of the outer oxides scale results in the nitrogen penetration into the inner oxides scale, and inner nitridation to form TiN occurs. Additionally, the oxidation mechanism was discussed by a model.