Mechanical and oxidation behavior of textured Ti2AlC and Ti3AlC2 MAX phase materials

Abstract

Highly textured Ti2AlC and Ti3AlC2 ceramics were successfully fabricated by a two-step fabrication process, and the Lotgering orientation factors for {00l} planes of textured Ti2AlC and Ti3AlC2 were calculated as 0.82 and 0.71, respectively. The effect of texturing was evaluated in terms of elastic modulus and hardness by macro- and micro-indentation. Moreover, the oxidation behavior of the MAX phases was investigated at 1300 °C in air, revealing that the oxidation was markedly anisotropic, where the textured side surface exhibited much better oxidation resistance, resulting from the rapid diffusion of Al element within its basal planes to form a protective Al2O3 scale on it. Furthermore, Ti2AlC had larger difference regarding oxidation behavior between the top and side surface than Ti3AlC2, correlated to its higher Al ratio, leading to higher texturing degree and more diffusion pathways to the outer surface to produce an Al2O3 layer already at the initial oxidation stage.