The cyclic oxidation behaviour of Ni-based superalloy GTD-111 with sulphur impurities at 1100 °C

The effect of sulphur on the cyclic oxidation of Ni-based superalloy GTD-111 was investigated. A cyclic oxidation experiment was performed for up to 200 cycles of 1 h exposure at 1100 °C. Even at the initial stage of 15 cycles, porosity increased with increasing sulphur content. The formation of pores along Cr2O3 layer grain boundaries was particularly pronounced. Increased porosity leads to an increase in spallation, which results in accelerated depletion of Cr and Al. As a result, continuity of an Al2O3 layer and cyclic oxidation resistance reduced with increasing sulphur content.