Combined use of GDOES and SEM + EDS for the microchemical study of oxide layers grown at high temperature on Nimonic 80 A nickel-based superalloy,

The microchemical structure of the oxide scale grown on a polycrystalline Nimonic 80 A nickel-based superalloy as a function of the air high-temperature treatment (up to 950°C) has been studied by means of the combined use of glow discharge optical emission spectrometry (GDOES), scanning electron microscopy with energy-dispersive spectrometry (SEM + EDS) and x-ray diffraction (XRD). The results disclose the morphology, the microchemical structure and the in-depth elemental chemical composition of the oxide layers and their variation as a function of the temperature of the air thermal treatment. Furthermore, GDOES, SEM + EDS and XRD results show the different oxidation behaviours of both main alloying and minor reactive elements that induce the formation of a stratified oxide structure.