The high-temperature oxidation of Nb-40Ti-15Al and the effect of Cr alloying and silicide diffusion coatings

Book · Sat Jul 01 04:00:00 EDT 1995

OSTI ID:72554

Cockeram, B V; Schmutzler, H J; Shyue, J; Hoshino, K; Meng, S; Wheeler, R; Fraser, H L ^[1]

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1. Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

The high-temperature oxidation resistance of Nb-40Ti-15Al-(0 or 5)Cr alloys has been studied. The kinetics and activation energy for the isothermal oxidation of Nb-40Ti-15Al are similar to pure titanium. Detailed TEM analysis of the oxidized Nb-40Ti-15Al alloy reveals that oxygen dissolution has produced a case layer by the decomposition of the matrix B2 phase into oxygen saturated alpha-Ti and an A15 phase. Internal oxidation of the A15 phase to form AlNbO{sub 4} occurred in the case layer near the scale/metal interface. The phase separated case layer evolved into a segregated oxide layer containing a co-continuous TiO{sub 2} phase. These morphologies of the oxide scale and case layer correlate well with the kinetic data, and suggest that oxygen dissolution in {alpha}-Ti and diffusion through TiO{sub 2} control the high-temperature oxidation rates. The Cr additions reduced the thickness of the case layer and slowed the oxidation kinetics, but did not change the mechanism. In addition, excellent cyclic oxidation resistant was provided by the silicide diffusion coatings.

• OSTI ID: 72554
• Report Number(s): CONF-941144--; ISBN 1-55899-265-0
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHROMIUM
CHROMIUM ALLOYS
CORROSION PRODUCTS
CORROSION RESISTANCE
EXPERIMENTAL DATA
METALLURGICAL EFFECTS
MICROSTRUCTURE
NIOBIUM ALLOYS
OXIDATION
PROTECTIVE COATINGS
TITANIUM ALLOYS
TITANIUM OXIDES
TRANSMISSION ELECTRON MICROSCOPY