Fracture and fatigue crack growth of bulk metallic glass alloys and their composites

Bulk metallic glasses exhibit extraordinary strength and elastic properties, but the lack of extensive plastic deformation and the catastrophic nature of failure limit the usefulness of the monolithic alloy. This work presents an overview of the results of fracture and fatigue crack growth experiments for a bulk metallic glass matrix composite with a Zr-Ti-Nb reinforcement phase precipitated in situ. The composite exhibits stable crack growth at stress intensities nearly double the fracture toughness of the monolithic glass. This is associated with the formation of a distributed damage zone at the crack tip. While the second phase had a marked effect on the fracture behavior, there was very little change to the fatigue crack growth results. Fractography suggests that the second phase particles are too small to cause crack bridging or significantly change the crack path.