Fracture surface morphology of Mg-based bulk metallic glass and composite during quasi-static and dynamic compressive deformation

The different fracture features developed during quasi-static and dynamic compressive deformation of Mg-based bulk metallic glass and composite reinforced by SiC particulate were investigated. Mg-based amorphous glass fractures on one major plane and shows a planar and smooth fracture surface upon quasi-static loading. The fracture surface of composite is rough, which is composed of a great deal of small mirror planes in quasi-static tests. Rugged fracture surfaces were observed both in Mg-based amorphous glass and composite during dynamic deformation. A large area of molten liquid spreads over the whole fracture surface, indicating more severe temperature rise occurs during dynamic deformation. When encountering SiC particulates during propagation, cracks cut through (sometimes being stopped inside the particulate) or bypass the particle. The fact that cracks cut through or bypass particles reflects the strong bonding at the particle-matrix interfaces and the effective load transfer from matrix to the reinforcing particles. The block function to crack propagation due to the presence of particles is expected for shear bands before cracking initiates inside the shear bands, avoiding the formation of major shear band and the catastrophic failure likely.