Fracture Behavior and Fracture Toughness of W Sintered Alloys

Fracture toughness behavior of W-Ni-Fe sintered alloys with three strength levels was investigated. With increasing tensile strength, dynamic fracture toughness Kld decreases dramatically, especially in the upper shelf. In low strength material, cracks propagate by the coalescence of boids created in binder, whereas in high strength material, cleavage fractures of W particles precede the void formation of binder. Fracture toughness Kmax significantly depends on specimen size. The Kmax increases with increasing specimen size, which is caused by larger amount of stable crack extension in larger specimens. No effect of loading rate on Kmax was observed.Relationship between the Charpy absorbed energy and dynamic fracture toughness was also investigated.