The effect of Cr and Mo addition on the oxidation behaviour of Ti-46.5Al-3.5Nb-2Cr-0.3B

The Oxidation behaviour of γ-TiAl alloys, Ti-46.5Al-3.5Nb-1Cr-1Mo-0.3B and Ti-46.5Al-3.5Nb-2Mo-0.3B were investigated at 900°C in air. The oxidation behaviour of these alloys were compared with Ti-46.5Al-3.5Nb-2Cr-0.3B (standard GKSS composition) to study the effect of Cr and Mo. The microstructure and the oxide layer were characterized by SEM and XRD as a function of oxidation time. The composition of the oxide layer was analyzed by EPMA line scan and elemental mapping. It has been observed that, the weight gain of the alloys under study with Mo addition is less as compared to the standard alloy while decrease in Cr content has improved the oxidation resistance, confirming the beneficial effect of Mo addition in improving the oxidation resistance of the γ -TiAl alloys.