Oxidation behaviour of the 47Nb 16Si 25Ti 8Hf 2Al 2Cr alloy sheet and vibrational spectroscopy

We report the chemical analysis of 47Nb 16Si 25Ti 8Hf 2Al 2Cr alloy sheet exposed in static air at 1200°C for 150, 300, 450, 600 and 900 seconds. This alloy exhibits linear oxidation kinetics. The dendritic phase M 5 Si 3 (with M=Hf and Ti) is observed to be not oxidised rapidly compared to the (Nb,...

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Bibliographic Details
Published in:Materials at high temperatures 2009-03, Vol.26 (1), p.15-20
Main Authors: Lefez, B., Jouen, S., Hannoyer, B., Bacos, M.-P., Beucher, E.
Format: Article
Language:English
Subjects:
Absorbance
Diffraction
Engineering Sciences
FTIR
high temperature
Materials
NbSi alloys
Niobium base alloys
Oxidation
Scanning electron microscopy
Signatures
Spectroscopy
Titanium
X-rays
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Summary:We report the chemical analysis of 47Nb 16Si 25Ti 8Hf 2Al 2Cr alloy sheet exposed in static air at 1200°C for 150, 300, 450, 600 and 900 seconds. This alloy exhibits linear oxidation kinetics. The dendritic phase M 5 Si 3 (with M=Hf and Ti) is observed to be not oxidised rapidly compared to the (Nb,Ti) ss , due to low oxygen solubility. Distribution of elements in the cross section of the oxide scales was analysed by energy-dispersive X-ray spectrometry and mapping in a scanning electron microscope. TiNb 2 O 7 and Nb 2 O 5 have been detected by X-ray diffraction. In addition, Fourier-transform IR spectroscopy showed absorbance peaks which are a clear signature of the formation of Si-O-Si, Si-O-Ti, and Si-O-Hf bonding in the oxidation layer. This analysis suggests that the film contains also amorphous silicates, not detected with X-ray diffraction.
ISSN:0960-3409
1878-6413
DOI:10.3184/096034009X435683