Dynamic fracture characteristics of Fe78Si9B13 metallic glass subjected to laser shock loading

The response of the Fe78Si9B13 metallic glass under different ratio of laser beam diameter (d) to die hole diameter (D) in micro scale laser punching was investigated. The typical fracture surface morphologies were observed using scanning electron microscope. The influence of the ratio d/D on dynamic deformation and fracture of metallic glasses foils was characterized. The results show that the dynamic fracture behavior of the Fe78Si9B13 metallic glass is sensitive to the ratio d/D. In the case of d/D = 1.75, the fracture surface is occupied by numerous liquid droplets, indicating that the temperature rise in an adiabatic shear band is beyond the melting temperature of the material. On the other hand, the fracture surface is covered dominantly with a mixture of shear steps, cellular patterns, liquid droplets and melted belts at d/D = 0.70. According to the general mechanical analysis, the specimen fails in a shear fracture mode at d/D = 1.75 due to the existence of shear stresses, while the fracture occurs in a tensile fracture mode at d/D = 0.70 under the effect of bidirectional tensile stresses.