Influence of volume fraction of primary α2 on the fracture toughness of Ti–Al–Nb alloy undergoing stress-induced martensitic transformation

The effect of volume fraction of primary α2 on fracture toughness of Ti–18Al–8Nb alloy, which undergoes stress-induced martensitic transformation (SIMT), was investigated. The fracture toughness of the alloy was found to decrease with an increase in volume fraction of primary α2. The results were explained on the basis of the effect of change in volume fraction of α2 on fracture toughness contributions due to SIMT as well as that due to the subsequent fracture process involving ductile fracture of the β/martensite/α2 microstructure.