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 non-affine displacements revealed that in both cases, the typical size of plastically rearranged domains varies depending on the strain amplitude and number of cycles, but remains smaller than the system size, thus pre -serving structural integrity of amorphous samples.

Automated summary

The research revealed that the potential energy and mechanical properties of amorphous materials can be influenced by variable-amplitude loading. Proper loading can rejuvenate well-annealed glasses, while improper loading can lead to a gradual decrease in energy states of poorly annealed glasses.