Characterization of <i>α</i>-Al<sub>2</sub>O<sub>3</sub> in Structural Isomers of Alumina Formed by Oxidation of Fe–Cr–Al Alloys

To understand the formation of structural isomers alumina (Al2O3) on surfaces Fe–Cr–Al alloys, cathodoluminescence (CL), X-ray photoelectron spectroscopy (XPS), and diffraction (XRD) were used. The alloys annealed under oxygen at a low partial pressure to focus initial Al2O3. XRD revealed that corundum (α-Al2O3) was predominantly formed alloy after annealing approximately 1100°C, whereas γ-Al2O3 θ-Al2O3 1000°C. CL peaks around 700 nm, which originated from Cr3+ ions in Al2O3, drastically increases by rising temperatures 1000 1100°C because increase chromium content Al2O3 scales XPS. EPMA surficial α-Al2O3 had striped patterns, similar those observed using imaging, indicating can be conveniently used for imaging analyzing inhomogeneous distribution alloys.