Complexity analysis of serrated flows in a bulk metallic glass under constrained and unconstrained conditions

For the present work, the Zr₅₅Cu₃₀Ni₅Al₁₀ (atomic percent) bulk metallic glass underwent room-temperature compression experiments in both the constrained and unconstrained conditions. For the constrained condition, samples were exposed to strain rates ranging from 2 × 10⁻⁵ s⁻¹ to 2 × 10⁻³ s⁻¹, while for the unconstrained case, the rates varied between 5 × 10⁻⁵ s⁻¹ and 2 × 10⁻³ s⁻¹. The serrated flow was modeled and analyzed using the refined composite multiscale entropy algorithm. Findings indicate that the complexity of the serration behavior increased with respect to the strain rate for both conditions. The increase in the complexity with increasing the strain rate is thought to be linked to a rise in the number of defect interactions that occur in the alloy during plastic deformation. Results also indicate that for a strain rate of 2 × 10⁻³ s⁻¹, the complexity of the serrated flow was the highest in the constrained condition, which corresponds to higher spatiotemporal correlations between slipping weak spots during a serration event. The microscopy results combined with the complexity analysis support the idea that the serration events, which correspond to defect interactions, are more spatially correlated in the constrained condition.