On the serration evolution of cellular bulk metallic glass monitored by fractal analysis

Abstract

Cellular bulk metallic glasses (BMGs) with varying porosities were fabricated by laser drilling, demonstrating different modes for the mechanical energy absorption process. The evolution of the elastic energy accumulation rate (Ep) and load drop parameter (L' = |d(load)/d(t)|) during the plastic-flow stages was examined using statistical analysis. The results have shown that the distribution of load drops follows a power-law scaling, and the three-parameter Weibull moduli (m) of both the Ep and L' values have fractal nature during the deformation process. The fractal dimension (D), fractal character measurement parameter (M) and fractal iteration sequence of the Weibull moduli (mEp−εp and mL′−εp) were used to characterize the serration evolution behavior under different conditions. The differences and relationships between the Ep and L' values were also discussed. The cellular BMG with stable and more iterative fractal sequences tend to exhibit relatively-stable deformation behavior, linearly growth energy absorption process and larger macroscopic plasticity.