| Summary: | Ductile metallic glass foams (DMGFs) are a
new type of structural material with a perfect
combination of high strength and toughness. Owing
to their disordered atomic-scale microstructures
and randomly distributed macroscopic voids, the
compressive deformation of DMGFs proceeds
through multiple nanoscale shear bands accompanied
by local fracture of cellular structures, which induces
avalanche-like intermittences in stress–strain curves.
In this paper, we present a statistical analysis,
including distributions of avalanche size, energy
dissipation, waiting times and aftershock sequence,
on such a complex dynamic process, which is
dominated by shear banding. After eliminating the
influence of structural disorder, we demonstrate
that, in contrast to the mean-field results of their
brittle counterparts, scaling laws in DMGFs are
characterized by different exponents. It is shown that
the occurrence of non-trivial scaling behaviours is
attributed to the localized plastic yielding, which
effectively prevents the system from building up
a long-range correlation. This accounts for the
high structural stability and energy absorption
performance of DMGFs. Furthermore, our results
suggest that such shear banding dynamics introduce
an additional characteristic time scale, which leads to
a universal gamma distribution of waiting times.
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