Effect of crystallographic texture on the anisotropy of fracture toughness in as-forged Ti-45Al-7Nb-0.4W-0.1B intermetallics

The anisotropy of fracture toughness is a crucial characteristic that impacts the service performance of TiAl intermetallics. This study investigated how the crystallographic texture affected the activation of slip and twinning systems, thereby impacting the anisotropy of fracture toughness in the as-forged Ti-45Al-7Nb-0.4W0.1B intermetallics. Results indicated that the as-forged TiAl intermetallics exhibited a high density of texture components, characterized by the {011}<100> texture in gamma phase and {0223}<2110> texture in alpha 2 phase. These textures significantly contributed to the anisotropy of fracture toughness in both the circumferential direction (CD) and the longitudinal direction (LD). The {011}<100> texture facilitated the activation of 1/2{111}< 110> ordinary dislocation slip system in the CD. Furthermore, the {0223}<2110> texture promoted the activation of {1100}<1120> prismatic slip system in the same direction. Notably, during the crack propagation process, the crack path exhibited a strong dependence on crystallography. The cleavage fracture surface analyses revealed that the preferential fracture planes were (100) and (111), which showed greater susceptibility to fracture than (001) and (110) planes. The findings of this study highlight the intricate relationship between the crystallographic texture and fracture toughness anisotropy in TiAl intermetallics, emphasizing the importance of texture in optimizing material performance.