Microstructure of an oxide scale formed on ATI 718Plus superalloy during oxidation at 850 degrees C characterised using analytical electron microscopy

Lech, S., Gil, A., Cempura, G., Agüero, A., Kruk, A., Czyrska Filemonowicz, A. 2019. Microstructure of an oxide scale formed on ATI 718Plus superalloy during oxidation at 850 degrees C characterised using analytical electron microscopy. International Journal of Materials Research 110, 1, 42-48 DOI: 10.3139/146.111675

The microstructure of a scale formed on the ATI 718Plus superalloy during oxidation at 850 degrees C for up to 1 000 h in air was characterised using various electron microscopy techniques taking advantage of recent development and capabilities of energy dispersive X-ray spectrometry. The study shows that a protective multilayered Cr2O3 scale was formed on this alloy; the outer Cr2O3 layer was coarse-grained, while the inner one was fine-grained. Underneath, a thin layer composed of TiNbO4 as well as an internal oxidation zone that was a dozen or so micrometres thick and consisted of individual Al2O3 precipitates had formed. The growth of the Cr2O3 layer caused the appearance of a chromium depletion zone, in which the gamma’ particles were not observed.

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