Mechanism of Na2 SO 4 ‐ Induced Corrosion of Molybdenum Containing Nickel‐Base Superalloys at High Temperatures: II . Corrosion in Atmospheres

The effect of content in the atmosphere on the corrosion of a molybdenum‐containing nickel‐base superalloy, Udimet 700, has been studied at 950°C. Catastrophic corrosion was observed for lower levels (<0.24%), and a highly porous scale was developed. No catastrophic corrosion was observed for higher levels (1–2%), and formation of internal Sulfides was observed to be the primary mode of degradation. Catastrophic corrosion was observed to be associated with the presence of in the melt along with and . Based on transport considerations, a mechanism is proposed to explain the rapid rate of corrosion in the presence of in the melt.