Basic Mechanisms Providing Oxidation Resistance in Structural Metals at High Temperatures.
Final rept. 21 Dec 72-20 Dec 73,
CINCINNATI UNIV OHIO DEPT OF MATERIALS SCIENCE AND METALLURGICAL ENGINEERING
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Oxidation characteristics of Ti-4.32 wt. Cb and Ti-4.37 wt. Ta exposed to pure oxygen or air are reported for the temperature range 982-1200C. The oxidation kinetics can best be described by either an initial parabolic or cubic rate which is followed by consecutive parabolic relationships. It is shown that 64 and 75 of the total amount of oxygen is dissolved in the metal matrix of the Ti-4.37 Ta alloy and 58 and 63 dissolves in the matrix of the Ti-4.32 Cb alloy during oxidation at 1000 and 1200C, respectively. X-ray diffraction studies reveal that the only oxide phases present are solid solutions of TiO2-Cb2O5 or TiO2-Ta2O5 formed during oxidation in oxygen. Oxidation in air leads to the formation of delta-TiN andor epsilon-TiN at the metaloxide interface, depending on the oxidation temperature. Hardness profiles and oxidation rate constants were used to calculate the diffusion coefficient of oxygen in both alloys. Electromotive force measurements were made. Modified author abstract
- Metallurgy and Metallography