On the fractal analysis of the serration behavior of a bulk metallic glass composite

Abstract

In this work, the plastic-flow dynamics of a Zr48Cu47.5Al4Co0.5 (at.%) bulk metallic glass composite (BMGC) under varying strain rates and stress gradients were investigated. Statistical analysis on the distributions of the elastic energy accumulation rates (Ep) and L' values (L' = |d(load)/d(t)|) was conducted. A self-similar structure was observed in the distribution of the plastic-flow serrations, including the serration shape and the L' value. The three-parameter Weibull moduli of both Ep and L' values of the plastic flows have shown that the Ep values can have a relatively high uniformity while the L' values demonstrate intrinsic large variations. The fractal dimensions of both the Ep and L' values are dependent on applied strain rates and stress gradients. During the evolution of plastic flows, the Weibull moduli of both Ep and L' values decreased with the increasing of plastic strains, regardless of varying strain rates and stress gradients. Moreover, the relationships between the elastic energy accumulation and release processes were also discussed. The present findings not only shed more light on the plastic-flow dynamics of BMGCs, but also open up a window for uncovering the underlying mechanisms of the serration behavior of related solid materials.