Oxidation of Ti<sub>3</sub>Al<sub>0.3</sub>Si<sub>0.7</sub>C<sub>2</sub> Compounds at 900-1200<sup>o</sup>C in Air

Ti3Al0.3Si0.7C2 compounds were synthesized via the powder metallurgical process, and oxidized isothermally and cyclically between 900 and 1200 oC in air. They had good thermal shock resistance, forming adherent oxide scales during cyclic oxidation. They oxidized to rutile-TiO2, α-Al2O3, and amorphous SiO2, together with gaseous escape of carbon. The oxide scales that formed during isothermal and cyclical oxidation were similar in that an outer (TiO2, Al2O3)-mixed scale, a thin intermediate Al2O3 layer, and an inner (TiO2, SiO2)-mixed scale formed. The outer scale formed by the outward diffusion of Ti4+ and Al3+ ions. The intermediate scale formed by the outward diffusion of Al3+ ions. The inner scale formed by the inward diffusion of O2- ions. No selective oxidation occurred from the early oxidation period. Keywords: Oxidation, powder metallurgy, Ti3SiC2, Ti3AlC2, Ti3(Al, Si)C2.