SEM, EDS, EPMA-WDS and EBSD characterization of carbides in HP type heat resistant alloys

The microstructure of centrifugally cast heat resistant alloys of the HP-series (Fe–35Ni–25Cr–0.4C, wt.%) contains several minor phases, like carbides (M7C3, M23C6 and MC). Several alloys are characterized by means of scanning electron microscopy in back-scattered electron imaging and energy dispersive spectroscopy, of electron probe micro-analysis by X-ray wavelength dispersive spectroscopy, and of electron back-scattered diffraction. On the one hand, scanning electron microscopy imaging in the back-scattered mode, associated with energy dispersive spectroscopy analysis and electron back-scattered diffraction, can lead to the identification of all phases, but with a lack of accuracy in certain cases. On the other hand, electron probe micro-analysis by X-ray wavelength dispersive spectroscopy alone can always provide a strict identification of all phases, with additional precise information on phase composition, including for light elements, which is important in the case of carbides.