ISSN:
1573-4889
Keywords:
air and oxygen oxidation
;
pressure influence
;
X-ray identifications
;
oxygen diffusion
;
oxidation mechanism
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Oxidation kinetics of Ti-4.37 wt.% Ta (1.19 at.%) alloy in either air or oxygen have been investigated in the temperature range 1258–1473 K and at three pressure levels: 0.013, 0.133, and 1.0 bar. X-ray data reveal only TiO2 (rutile) as the main oxide and, in addition, TiO2, S-TiN, and ɛ-TiN at the metal surface for oxidation in air at 1273 K. The ɛ-TiN phase was not detected at higher temperatures. Electron microprobe analyses are used to determine the concentration profiles of Ti, Ta, O, and N across the oxide scale and in the metal. Microhardness traverses follow the oxygen distribution in the alloy. The oxygen diffusion coefficient,D = 60.8 exp(−235.1/RT), as determined from weight-gain measurements, is in reasonable agreement with that calculated from microhardness data. The oxidation mechanisms for oxidation of the alloy in air or oxygen are proposed.The existence of interstitial Ti cations in the oxide is suggested.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00603992
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