Effect Of Silver Addition On Surface Morphology Of Al2O3 Scales During Oxidation Of β-NiAl
ZHANG Xuejun; WU Weitao; NIU Yan
State Key Laboratory for Corrosion and Protection; Institute of Metal Research; The Chinese Academy of Sciences; Shenyang 110016
Cite this article:
ZHANG Xuejun; WU Weitao; NIU Yan. Effect Of Silver Addition On Surface Morphology Of Al2O3 Scales During Oxidation Of β-NiAl. Acta Metall Sin, 2005, 41(4): 369-374 .
Abstract The effect of adding small amounts of Ag to β-NiAl on surface morphology of alumina scale during the oxidation at 1000-1100oC and the oxidation kinetics of β-NiAl and NiAl-1Ag were investigated by TGA and SEM/EDS. The kinetics of β-NiAl presents two parabolic stages controlled by the growth of metastable alumina and stable α-Al2O3, respectively, while those of NiAl-1Ag are composed of three different parabolic stages controlled by the growth of γ-Al2O3, θ-Al2O3 and α-Al2O3, respectively. The additions of small amounts of Ag to β-NiAl favors the phase transformation from metastable alumina to α-Al2O3, while this effect disappears for an Ag content above 5% at 1000oC. Finally, the addition of 0.5% Ag to β-NiAl does not affect the surface morphology of Al2O3 at 1100oC.
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