Ionic Segregation on Grain Boundaries in Thermally Grown Alumina Scales
作者： Bruce A. Pint , Kinga A. Unocic
DOI: 10.3184/096034012X13343209167745
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摘要: This study first examined segregation behaviour in the alumina scale formed after 100 h at 1100 C on bare and MCrAlYHfSi-coated single-crystal superalloys with {approx}10 ppma La Y. For superalloy, Hf Ti were detected grain boundaries of inner columnar layer. Increasing oxidation temperature to 1200 for 2 did not change behavior. With bond coating, both Y segregated as expected. However, there was evidence Ti-rich oxide particles near gas interface suggesting that diffused from superalloy through coating. To further understand these observations multiple dopants, other alumina-forming systems examined. Alumina boundary co-segregation is common FeCrAl alloys. Co-segregation observed co-doped NiAl. No NiCrAl only a 19 addition, however, adherent.
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