Short-term corrosion behavior of polycrystalline Ni3Al-based superalloy in sulfur-containing atmosphere

Harsh service environment especially in sulfur-containing atmosphere and complex structures of dominant γ' + γ dendrite, interdendritic region and interface region have significant effect on service life of polycrystalline Ni3Al-based superalloys. In this work, hot corrosion behavior of polycrystalline Ni3Al-based superalloy in sulfur-containing atmosphere was studied at 900 °C. Growth behaviors of corrosion products were analyzed by X-ray Photoelectron Spectroscopy, Raman spectrometer, Scanning Electron Microscope and Transmission Electron Microscope. The results showed that the growth behaviors of corrosion products were different in different regions. Corrosion products in interdendritic regions were Ni3S2 and Al2O3. While, as for dominant γ' + γ dendrite and interface regions, corrosion products were mainly composed of Ni3S2, Cr3S4 and mixed oxides. However, though the corrosion products are similar in composition, they have different growth mechanism. Spatial structure and precipitates were observed to analyze and explain the reasons for difference of corrosion behaviors in different regions.