Effect of Ti–Al–Cr coatings on the high temperature oxidation behavior of TiAl alloys

The high temperature oxidation behavior of TiAl alloys coated with Ti–Al–Cr alloys using magnetron sputtering method was studied. The results showed that Ti–Al–Cr coatings improved the oxidation resistance of TiAl alloys. The weight gains at 950°C for Ti–Al–Cr coatings are more than those at 1000°C. Oxide formed on the surface of Ti–50Al–15Cr coating after oxidation consisted of Al2O3, whereas oxide formed on the surface of Ti–50Al–10Cr coating after oxidation is composed of a mixture of a large portion of Al2O3 and a small portion of TiO2. The effect of Ti–Al–Cr coatings on the improvement of oxidation resistance of TiAl alloys results from thermodynamic and kinetics factors contributing to Cr effect.