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Article

Accessing a broader range of energy states in metallic glasses by variable-amplitude oscillatory shear

The influence of variable-amplitude loading on the potential energy
and mechanical properties of amorphous materials is investigated
using molecular dynamics simulations. We study a binary mixture that
is either rapidly or slowly cooled across the glass transition
temperature and then subjected to a sequence of shear cycles with
strain amplitudes above and below the yielding strain. It was found
that well annealed glasses can be rejuvenated by small-amplitude
loading if the strain amplitude is occasionally increased above the
critical value. By contrast, poorly annealed glasses are relocated
to progressively lower energy states when subyield cycles are
alternated with large-amplitude cycles that facilitate exploration
of the potential energy landscape. The analysis of nonaffine
displacements revealed that in both cases, the typical size of
plastic rearrangements varies depending on the strain amplitude and
number of cycles, but remains smaller than the system size, thus
preserving structural integrity of amorphous samples.