Deformation and Fracture Analysis of a Duplex γ-TiAl Alloy during Low Cycle Fatigue
Isothermal low cycle fatigue (LCF) behaviours of a third generation titanium aluminide based γ-TiAl alloy with duplex microstructure were investigated under the various test conditions, including temperature (550°C-750°C), total strain amplitude (0.3%-0.6%) and environment (air and vacuum), in order to clarify the fatigue life, deformation characters and fracture process of the alloy during LCF. The plastic strain accumulation has a great contribution to LCF damage. With increasing total strain range, LCF life decreases distinctly. Under the small total strain amplitude (≤0.4%), the increase of test temperature enforces microstructure resistance to LCF fracture. However, the increase of test temperature together with large total strain amplitude (>0.5%) accelerates the microstructural degradation, which behaves the dissolution of α2 lamellae and recrystallization of γ phase, resulting in great LCF damage. Moreover, environment brittlement during high temperature exposure to air influences the initiation process of fatigue cracks. The fracture mechanisms at various test conditions were analyzed.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
W. F. Cui et al., "Deformation and Fracture Analysis of a Duplex γ-TiAl Alloy during Low Cycle Fatigue", Materials Science Forum, Vols. 539-543, pp. 1571-1576, 2007