Fatigue Property of Intermetallic Compound TiAl alloy Coated with ZrO2 and CoNiCrAlY at Elevated Temperature.

The fatigue mechanism of a intermetallic compound TiAl alloy, coated with ZrO2 and CoNiCrAIY alloy by the plasma spraying, was studied in vacuum at 1073 K using a SEM-servo testing machine. Especially, the mechanism of crack growth in coating layer and the fatigue process near the interface between TiAl substrate and coating layer were observed from the mesoscopic viewpoint. The results indicate that the fatigue strength of coated TiAl alloy and uncoated TiAl alloy are almost similar. The fatigue property of coated TiAl alloy is controlled by the mechanism of mesoscopic crack initiation and growth in coating layer and the fatigue process near the interface with delamination. It was successful for coated TiAl alloy to apply the mesoscopic fracture mechanics to reveal the factor controlling fatigue life.