Cyclic oxidation of Ti3Al-based alloy

The effect of the annealing temperature on the cyclic oxidation behavior of the Ti-24Al-11Nb (at.%) alloy during 120 h exposure at 600°C and 900°C in air was investigated using various techniques. Oxidation temperature greatly influences the morphology and composition of the formed scale. Namely, in contrast to the compact external layer formed during oxidation at 600°C, the multilayered scale formed by external oxidation and internal oxidation zone were observed after annealing at 900°C. Main oxidation products are Al2O3 and TiO2. Titanium and aluminum nitride layers formation, as well as niobium diffusion in to the external scale, retards oxygen diffusion in to the matrix and inward titanium diffusion to the external scale.