High Temperature Oxidation of Ti-47%Al-1%Mn Alloy

Abstract

The thermomechanically treated Ti–47%Al–1%Mn alloy was oxidized in air at 1073, 1173, and 1273 K . When compared to Ti–47%Al, the oxidation resistance of Ti–47%Al–1%Mn was better at 1073 K, slightly better at 1173 K, but poorer at 1273 K . The scale adherence was improved by the addition of Mn to a certain degree. The oxidation products were TiO₂ and α-Al₂O₃, together with a very small amount of MnTiO₃, Mn₂O₃, TiN and Ti₂AlN . Within the (TiO₂, Al₂O₃) oxide grains, some dissolution of Mn was noticed. The oxidation progressed via the outward diffusion of Ti ions to form the outer TiO₂ layer, and the inward transport of oxygen to form the inner (TiO₂+Al₂O₃) mixed layer, between which an intermediate Al₂O₃ layer existed. Subsurface zone within the metal phase was depleted in Al.