Effect of Cr on the oxidation behavior of Ti-46Al-2V alloy

Titanium aluminide alloys are already widely used because of excellent mechanical properties, but are limited to low temperature applications due to insufficient high temperature oxidation resistance. When these alloys are subjected to oxidation in air the scale is not a protective Al2O 3 layer, but a mixture of Al2O3 and TiO 2. The oxidation resistance of TiAl intermetallics is known to be significantly affected by the addition of alloying elements. The oxidation behavior of Ti-46Al-2V (composition in at. %) was studied and compared with the ones of the same alloy containing respectively 7, 10 and 14 % Cr. Isothermal tests were conducted in air at 850 and 950 °C The scale's morphology and composition were studied by means of SEM/EDS and X-ray diffraction. From weight gain curves and cross-sectional microscopy after oxidation exposure it was found that more than 7 at.% of Cr improves the oxidation resistance of the alloy, although it simultaneously reduces its toughness