Oxidation-Induced Decrease in Impact Resistance of TiAl4822 Used in Jet Engine Blades

Oxidation embrittlement at operating temperatures is a major concern in TiAl4822 that are widely used in jet engine blades. Previous studies on oxidation embrittlement of TiAl alloys, including TiAl4822, have focused primarily on tensile properties under specific oxidation conditions. In this study, we examined embrittlement behavior from the perspective of impact resistance that more closely reflects real-world requirements using samples oxidized at various temperatures and for different durations. Even mild oxidation (e.g., 10 min at 500 °C) caused embrittlement at 25 °C. However, the change in the degree of embrittlement under more severe oxidation conditions (e.g., 1h at 900 °C or 1,000 h at 700 °C) was not significant. Conversely, extreme embrittlement occurred at 1100 °C and above. This was attributed to the influence of an altered layer containing cracks that was formed at the interface between the base metal and the oxide layer. No embrittlement occurred at a test temperature of 200 °C. Preventing moisture adhesion on the oxidized surface reduced embrittlement. These results suggest that environmental embrittlement due to the preferential adsorption of moisture on oxidized surfaces may be an additional embrittlement factor, alongside previously recognized factors such as oxygen penetration.