Kinetic and Thermodynamic Aspects of High-Temperature Oxidation of Selected Ti-Based Alloys

In the presented work, high-temperature cyclic oxidation of pure Ti, Ti-7.8wt.%Si, Ti- 45.6wt.%Al and Ti-11.7wt.%Al-7.2wt.%Si alloys at 750 – 1050 °C in air were studied. It was found that both Si and Al strongly reduce the oxidation rate of titanium, mainly up to 850 °C. They incorporate into the oxide scales and reduce penetration rate of oxygen towards the metallic substrate. Mechanism of the barrier effects of the elements is discussed with respect to their distribution in alloys. It was observed by comparison of Al-containing and Si-containing alloys, that the influence of Si on the oxidation kinetics is significantly stronger. It can be supposed that a synergic effect of silicon and nitrogen is a reason for this behavior.