Transition of nano-scale to micro-scale on fracture surface of Zr65Cu17.5Ni10Al7.5 bulk metallic glass

The author reports the observations of nano-scale and micro-scale patterns on fracture surface of Zr65Cu17.5Ni10Al7.5 bulk metallic glass. The nano-scale patterns or flat shear plane are generated by crack front waves in the beginning of crack initiation. In addition to this kind of pattern, it is also found that there is a micro-scale pattern, i.e., the vein pattern which is induced by dynamic instability of a rapidly propagating crack front. The decrease in the viscosity within the shear bands due to shear softening causes stress state to fluctuate, that finally leads to changes of fracture mode during the fracture process.