Oxidation of Nb--Mo alloys over the temperature range of 485 to 935$sup 0$C

Journal Article · Mon Oct 01 04:00:00 EDT 1973 · Denki Kagaku, v. 41, no. 10, pp. 753-758

OSTI ID:4362404

Yamawaki, M; Kanno, M; Mukaibo, T

The oxidation behavior of Nb--2.5, 5.0, and 7.5 at.% Mo alloys was investigated in detail by means of thermogravimetric measurement, x-ray diffraction, and metallographic methods. The tests were conducted at temperatures ranging from 485 to 935 deg C in dry oxygen at a pressure of 0.20 atm. Generally the para-linear or pseudo para-linear type of oxidation curve was obtained. The apparent linear oxidation rate of the alloys was calculated from the post transition part of each oxidation curve and was found to be generally lower than that of pure niobium. Breakaway of a thin protective layer formed at low temperatures was delayed by molybdenum alloying. At temperatures ranging from 635 to 735 deg C on Nb--5.0 or 7.5 at.% Mo alloy, a thin protective layer of NbO/sub 2/ was formed to give a high oxidation resistance, under which NbO/sub 2/ platelets were formed abundantly. The B-Nb/sub 2/O/sub 5/ was for the first time identified in the scales on the Nb--Mo alloys at temperatures ranging from 685 to 835 deg C. Oxidation of Nb--2.5 at.% Mo alloy at 835 deg C was found to show a peculiar parabolic to plateau-like type rate transition and this was attributed to the T to B structural transition of Nb/sub 2/O/sub 5/ in scale. (auth)

• Research Organization: Tokyo Univ.
• NSA Number: NSA-29-016196
• OSTI ID: 4362404
• Journal Information: Denki Kagaku, v. 41, no. 10, pp. 753-758, Journal Name: Denki Kagaku, v. 41, no. 10, pp. 753-758; ISSN DNKKA
• Country of Publication: Japan
• Language: English

Related Subjects

*MOLYBDENUM ALLOYS-- OXIDATION
*NIOBIUM BASE ALLOYS-- OXIDATION
METALLOGRAPHY
N50210* --Metals
Ceramics
& Other Materials--Metals & Alloys--Corrosion & Erosion & Surface Phenomena
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION