Structure characterization of the oxide film on FGH96 superalloy powders with various oxidation degrees

The structure of the oxide film on FGH96 alloy powders significantly influences the mechanical properties of superalloys. In this study, FGH96 alloy powders with various oxygen contents were investigated using high-resolution transmission electron microscopy and atomic probe technology to elucidate the structure evolution of the oxide film. Energy dispersive spectrometer analysis revealed the presence of two distinct components in the oxide film of the alloy powders: amorphous oxide layer covering the γ matrix and amorphous oxide particles above the carbide. The alloying elements within the oxide layer showed a laminated distribution, with Ni, Co, Cr, and Al/Ti, which was attributed to the decreasing oxygen equilibrium pressure as oxygen diffused from the surface into the γ matrix. On the other hand, Ti enrichment was observed in the oxide particles caused by the oxidation and decomposition of the carbide phase. Comparative analysis of the oxide film with oxygen contents of 140, 280, and 340 ppm showed similar element distributions, while the thickness of the oxide film varies approximately at 9, 14, and 30 nm, respectively. These findings provide valuable insights into the structural analysis of the oxide film on FGH96 alloy powders.