The anelastic origin of mechanical cycling induced rejuvenation in the metallic glass

Mechanical cycling is one of the effective methods to rejuvenate metallic glasses (MGs) and improve their mechanical properties. The anelastic origin of the rejuvenation by mechanical cycling in a La30Ce30Ni10Al20Co10 MG was investigated via differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). We demonstrate that mechanical cycling promotes the activation of flow defects with short relaxation times, leading to anelastic strains and therefore considerable energy storage, which manifests itself as larger relaxation enthalpy on the DSC curves of MGs. However, the MGs release the excess relaxation enthalpy caused by anelastic strain with time, thus suppressing atomic mobility and elevating β relaxation activation energies. The strategy of mechanical cycling at small strains, as demonstrated in the current work, can expand the energy states of MGs over a wide range of relaxation enthalpies.