Fracture toughness of Ti-15Al-8Nb alloy under mixed mode I/III loading

Fracture toughness of Ti-Al-Nb alloys under mixed mode I/III loading was studied. ► Alloys undergo stress-induced martensitic transformation (SIMT) at four grain sizes. ► Fracture toughness under mixed mode in alloys with SIMT was explored for the first time. ► Fracture toughness under mixed mode loading was higher than that under mode I loading. ► This was due to effect of stress/strain fields ahead of mixed mode crack on martensitic zone.