Influences of Al concentration and Nb addition on oxidation behavior of Ti2AlC ceramics at high temperatures

ABSTRACT A titanium aluminum carbide, Ti2AlC, which is classified among MAX phase ceramics, was studied as a potential candidate for various mechanical components used in high-temperature applications. The impact of its chemical composition on its high-temperature oxidation process was determined. Ti2AlC powders with various Al contents and with or without Nb addition were synthesized via a conventional reaction technique followed by 16 h of annealing in vacuum at 1300°C. The synthesized Ti2AlC powders were consolidated by means of 15 min of pulsed electric current sintering at a die temperature of 1300°C in vacuum under a uniaxial pressure of 30 MPa. In the presence of an aluminum reservoir in the form of TiAl3, Ti2AlC has excellent resistance against high-temperature oxidation. The promising results concerning the addition of Nb to TiAl provided the rationale for a similar modification of Ti2AlC. The results of oxidation tests on Nb-doped Ti2AlC likewise showed excellent oxidation resistance. Alloying with Nb can improve the oxidation resistance of Ti2AlC with low Al content, allowing the formation of a protective Al2O3 scale and inhibiting the growth of TiO2.