Elevated-temperature oxidation behavior of titanium silicide and titanium silicide based alloy and composite

The oxidation behavior of Ti5Si3 has been studied in air in the temperature range of 1200-degrees-C to 1400-degrees-C. The oxidation kinetics is slower than that predicted by the parabolic-rate law equation at 1200-degrees-C, but is sharply enhanced beyond a temperature of 1300-degrees-C. The oxidation kinetics of a Ti5Si3-8 wt pct Al alloy and a Ti5Si3-20 vol pct TiC composite at 1200-degrees-C has also been investigated and compared to that of Ti5Si3. Alloying with Al does not alter the oxidation resistance much, but the presence of TiC reinforcements enhances the rate of oxidation significantly. The oxidation products have been identified and the mechanism of oxidation has been analyzed using thermodynamic and kinetic considerations.