Crossover from free propagation to cooperative motions of shear bands and its effect on serrated flow in metallic glass

The serrated flow dynamics and shear band motions can be controlled by changing aspect ratio (AR) and deformation degree. With decreasing ARs, the serration pattern transforms from a sharp-peak type with uniform size into a complex type with various sizes, the ratio of stress drop time tD to rising time tR for serrated flow increases, the time intervals tn between adjacent serrations decreases. The serrated flow exhibits a crossover from Gaussian-type distribution to power-law-type distribution with decreasing ARs. This crossover is mainly governed by a transition from single-shear-band dominated deformation to cooperative motions of multiple shear bands dominated deformation. Additionally, such crossover can also be governed by deformation degree.