Fractal analysis on the uniformity between the shear bands and serrated flows of a Zr-based bulk metallic glass

Abstract

It is challenging to unravel the relationship between the serrated flows and complex shear bands of bulk metallic glasses (BMGs) when they are evolving. In this work, fractal analyses of the one-dimensional load-drop signals in time domain and the two-dimensional shear-band patterns were conducted at different strain stages. With the increase of strains, the fractal dimensions of both shear-band patterns and serrated flows show similar continuous increasing trends. From the perspective of chaos degree, a positive correlation between the load-drop distributions and shear-band patterns was obtained. The Hurst exponents less than 0.5 show that the distribution of load drops has a strong negative correlation behavior and there is a negative feedback mechanism in the development of shear bands. Moreover, at different strain stages, the fractal dimensions and Weibull moduli have indicated that the load drops demonstrate a relatively-high uniformity initially and then stabilize at a low uniformity, which is related to the regular shear-band patterns with fractal structure. The findings provide further understandings between the formation of shear bands and serrated flows of BMGs, which also open a new window to uncover the plastic deformation mechanisms of BMGs using fractal analysis.