OXIDATION OF 90 Cb-10 Ti ALLOY IN THE TEMPERATURE RANGE 500-1200 C

Journal Article · Sun Sep 01 04:00:00 EDT 1963 · Trans. Am. Soc. Metals

OSTI ID:4659362

Kolski, T L

Reaction rates of 90 Nb--10 Ti alloy with oxygen at 1 atm were determined gravimetrically at temperatures between 500 and 1200 deg C, for reaction times ranging from 25 to 200 hr. At 700 deg C, a high oxidation rate follows a breakaway transition in kinetics after 15 to 20 hr from a rate which originally decreases with time. A mild breakaway transition occurs at 600 deg C after about 60 hr, but total oxygen absorption is low even after 150 hr. Oxidation rate at 500 deg C is extremely slow, total uptake of oxygen amounting to only 1.4 mg per cm/sup 2/ after 200 hr. Above 700 deg C a rate inversion occurs with increasing temperature; oxidation rate passes through a minimum near 800 deg C, then rises with further temperature increase. Analysis and x-ray diffraction patterns of outer scales formed on 90 Nb-10 Ti at 800 deg C or higher tentatively indicate that these consist of solid solutions of TiO/sub 2/ in Nb/ sub 2/O/sub 5/. The outer scale formed at 700 deg C is not fully oxidized and exhibits a diffraction pattern differert from the one characteristic of scales formed at higher temperatures. Little or no loose outer scale is formed at lower temperatures, but the absorbed oxygen forms a hard case of tightly adherent oxide. Oxygen contaminated zones are formed under the outer oxide growth at higher temperatures and attain thicknesses which increase markedly with oxidation temperature. A tentative mechanism for the accelerated oxidation observed near 700 deg C is proposed; it is based on severe surface cracking of the oxygen- contaminated zone. (auth)

• Research Organization: E.I. du Pont de Nemours and Co., Inc., Wilmington, Del.
• NSA Number: NSA-17-037486
• OSTI ID: 4659362
• Journal Information: Trans. Am. Soc. Metals, Journal Name: Trans. Am. Soc. Metals Vol. Vol: 56
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ADHESION
ADSORPTION
CHEMICAL REACTIONS
CORROSION
CRACKS
DIFFRACTION
GRAVIMETRY
HIGH TEMPERATURE
METALS, CERAMICS, AND OTHER MATERIALS
NIOBIUM ALLOYS
NIOBIUM OXIDES
OXIDATION
OXYGEN
QUANTITATIVE ANALYSIS
REACTION KINETICS
SOLID SOLUTIONS
SURFACES
TEMPERATURE
THICKNESS
TITANIUM ALLOYS
TITANIUM OXIDES
WEIGHT
X RADIATION