INFLUENCE OF ALUMINUM ON THE OXIDATION OF TITANIUM BETWEEN 550-DEGREES-C AND 750-DEGREES-C

In order to study the influence of aluminium on the oxidation resistance of titanium at high temperature, a range of binary alloys containing 1.65, 3, 5 and 10 wt.% of aluminium was prepared. Their oxidation kinetics were studied at temperatures between 500 and 750 °C using either continuous thermogravimetry or daily weighing for periods of up to several thousand hours. The results obtained for oxidation in air confirm the beneficial role of aluminium which has been observed previously for oxidation in oxygen. With regard to morphology and structure, aluminium modifies the internal structure of the oxide layers and their growth laws. A general dispersion of aluminium in rutile is observed, although a concentration of this phase is noted near the external interface; there is also a reduction in the amount of oxygen dissolved in the metal substrate which is related to the aluminium content in the alloy. Moreover, the presence of aluminium also modifies the adhesion of the oxide layers to the substrate. © 1990.