Transient alumina phases transformation

The morphology of alumina scales on NiAl depends on the oxidation temperature and oxidation time. At lower temperatures (<1400 K). the metastable oxide phases 7-and 0-Al2O3 are formed initially. These metastable phases transform into a-AFO, during a transient time which decreases with higher temperature (> 1200 K) [24—26J. 

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