Non-destructive evaluation of alumina scale on heat-resistant steels using cathodoluminescence and X-ray-excited optical luminescence

[Display omitted] •CL and XEOL imaging allows us to identify Al2O3 scale on Fe–Al alloy.•Surface morphology of Al2O3 scale is observable by capturing CL and XEOL images.•Al2O3 scale thickness can be non-destructively determined from its CL intensity.•CL and XEOL analysis are applicable to non-destructive evaluation of oxide scales. We propose a non-destructive measurement method to identify Al2O3 scale on an Fe–Al alloy and to evaluate the morphology and thickness of the scale using cathodoluminescence (CL) and X-ray-excited optical luminescence (XEOL). CL and XEOL images allowed us to distinguish the Al2O3 scale from other scales from the luminescent color of the Al2O3, and to observe the surface morphology of the scale. The CL intensity of a peak at 695 nm in the spectra was used to determine the scale thickness. Therefore, CL and XEOL analysis could be used in the non-destructive evaluation of oxide scales on heat-resistant steels.