Relationship between fracture toughness and microstructure of Ti–6Al–2Sn–4Zr–2Mo alloy reinforced with TiB particles

Ti–6Al–2Sn–4Zr–2Mo alloy matrix composites reinforced with various volume fractions of TiB particles were fabricated using the blended elemental powder method in the present study. The static and dynamic fracture toughness tests were carried out on the composites at room temperature in order to understand the fracture mechanism. The dynamic fracture toughness value is fairly smaller than the static fracture toughness value. The ratio of dynamic fracture toughness value to static fracture toughness value increases with increasing the volume fraction of TiB particles. The fracture toughness value increases with increasing the degree of crack deflection which is greater under static conditions than under dynamic conditions. The fraction of TiB particles on the fracture surface is greater in the specimen with greater volume fraction of TiB particles, and is greater under dynamic conditions than under static conditions. Since the debonding of TiB particles from the matrix and shearing of TiB particles occurs easily, the fracture toughness value of composites decreases with increasing the volume fraction of TiB particles.