On oxide formation on a single crystalline Ni-based superalloy at 900 °C in SO2 containing atmosphere: The effect of surface treatment

The oxidation behavior of the single crystalline SCA425+ (17Cr-10Al-3Ta-Ni bal.) after two different surface finish procedures (grinding and polishing) was investigated after cyclic exposures at 900 degrees C in SO2 containing atmosphere up to 260 h. The microstructure and chemistry of the produced oxide scales were studied using highresolution methods, SEM/EDX, TEM, and STEM. The investigation revealed that grinding provides more effective diffusion paths, so that the material is able to form a protective continuous alumina layer, while an extensive internal oxidation takes place on the polished sample. In addition, a numerical model, based on the cellular automata approach, was developed and used to consider the effect of dislocation pipe diffusion in combination with diffusion processes and oxide formation. Good agreement between the model and experimental results was obtained.

Automated summary

The oxidation behavior of the single crystalline SCA425+ after cyclic exposures in an atmosphere containing SO2 was studied following two different surface finish procedures. Grinding was found to provide more effective diffusion paths for the material to form a protective alumina layer, while extensive internal oxidation occurred on the polished sample. Additionally, a numerical model based on cellular automata approach was developed to consider the interaction of dislocation pipe diffusion, diffusion processes, and oxide formation, showing good agreement with experimental results.