The DRV–DRX balance governs high-temperature rupture life in TiAl alloys

This study demonstrates that the dynamic recovery–dynamic recrystallization (DRV–DRX) balance is the primary factor determining the rupture life of TiAl alloys at 900 ℃. Stress-rupture tests reveal strong stress sensitivity, with lifetime decreasing from 587 ± 24.2 h at 125 MPa to 50 ± 7.1 h at 185 MPa. Two distinct fracture modes are identified: lamellar fracture induced by lamellar bending and cracking, and void-dominated fracture associated with intergranular damage. Lamellar deformation is orientation-dependent: small-angle lamellae accommodate deformation through coherent twinning and dislocation glide, which suppress stress localization, whereas large-angle lamellae favor faulted twins and incoherent twin boundaries, which accelerate crack initiation. The rupture life is primarily dictated by the balance between DRV and DRX. When DRV and DRX are balanced, dislocation annihilation and twin-assisted recovery stabilize the microstructure, suppress interfacial stress incompatibility, and extend lifetime. Once the balance is lost, rapid DRX generates high grain boundary density and stress concentration, leading to void formation and premature failure. These findings establish a new DRV–DRX balance framework for understanding high-temperature rupture in TiAl alloys and highlight potential processing and alloying strategies to prolong service life in aero-engine applications.