Study on the time-dependant fracture behavior of Ti2AlNb based alloy

The time-dependant fracture behaviors of Ti–24Al–14Nb–3V–0.5Mo alloy, i.e., high cycle fatigue (HCF) at room temperature, cyclic notch stress rupture at 650 °C were studied. Microstructure and fractograph were examined by means of scanning electron microscope using back scattered electron image and secondary electron image, respectively. The HCF limit of Ti–24Al–14Nb–3V–0.5Mo alloy at room temperature is 670 MPa. O phase precipitation in continuous B2 matrix is beneficial to improve the fatigue limit of Ti–24Al–14Nb–3V–0.5Mo alloy. Limited step of HCF behavior is crack initiation controlling. Effect of stress level on the cyclic notch stress rupture life is stronger than that of notch radii. In the peripheral zone, high temperature crack fatigue growth is the dominant mechanism, while in the middle zone, creep void growth–linkage is the dominant mechanism.