Nondestructive, Rapid Identification of Aluminum Nitride and Internal Alumina Scales on a Heat-Resistant Alloy Using Cathodoluminescence

Abstract

A nondestructive method to rapidly identify AlN precipitates and internal Al2O3 scales on Ni–Cr–Al alloy via cathodoluminescence (CL) analysis is proposed. AlN could be instantly distinguished from Al2O3, Cr2O3, and CrN based on the detection of violet luminescence in CL images. Moreover, an Al2O3 scale beneath a surface Cr2O3 scale with the thickness below 3.2 μm can be rapidly identified based on a peak at 695 nm in the CL spectra of the alloy surface with no requirement for a destructive cross-sectional analysis. The exposure time for the CL images and the acquisition time for the CL spectra were within 1 min. Therefore, CL analysis may provide a rapid, nondestructive, analytical method for identifying AlN precipitates and internal Al2O3 scales in heat-resistant alloys.