TEM study of the initial oxide scales of Ti2AlC Original Research Article

This paper presents a detailed microstructural analysis of the crystallographic relationships between α-Al2O3 oxide scale and Ti2AlC parent material, and examines the atomic diffusion and formation of oxide scale on Ti2AlC during the initial oxidation stage at 1200 °C. It is shown that the α-Al2O3 oxide scale can be either a continuous or a discontinuous capping layer on Ti2AlC. A Ti-rich intermediate layer that consists mostly of TiC interrupts the continuity of the α-Al2O3 layer. The channels for inward diffusion of O and outward diffusion of Ti and Al run not only along grain boundaries of α-Al2O3, but also through the Ti-rich intermediate layer. The outward diffusion of Al atoms is either parallel to the (0 0 1) basal plane or parallel to prism planes of Ti2AlC. Crystallographic orientation relationships between α-Al2O3 oxide scale and Ti2AlC were observed: image // image, image // image and image // image, image // image.