Quasi-in-situ observing the growth of native oxide film on the FeCr15Ni15 austenitic alloy by TEM

Element Cr imparts non-crystallinity effect on the oxide film on iron. Therefore, in contrast with the oxidation of iron, the oxidation process of Fe-Cr alloys is more complicated. By means of high angle annular dark field scanning transmission electron microscopic (HAADF-STEM) imaging combined with electron-energy loss spectroscopy (EELS) and super-X electron dispersed spectroscopy (Super-X EDS) techniques in an aberration-corrected TEM, we have clarified the evolution in the oxide film formed on an FeCr15Ni15 alloy. The oxide film is identified to be amorphous at the initial oxidation stage, but tends to become crystalline in the inner layer after aging in air.