Shear band healing in amorphous materials by small-amplitude oscillatory shear deformation

Abstract: The effect of small-amplitude periodic shear on annealing of a shear band in binary glasses is investigated using molecular dynamics simulations. The shear band is first introduced in stable glasses via large-amplitude periodic shear, and then amorphous samples are subjected to repeated loading during thousands of cycles at strain amplitudes below the yield strain. It was found that with increasing strain amplitude, the glasses are relocated to deeper potential energy levels, while the energy change upon annealing is not affected by the glass initial stability. The results of mechanical tests indicate that the shear modulus and yield stress both increase towards plateau levels during the first few hundred cycles, and their magnitudes are largest when samples are loaded at strain amplitudes close to the yield strain. The analysis of nonaffine displacements reveals that the shear band breaks up into isolated clusters that gradually decay over time, leading to nearly reversible deformation within the elastic range. These results might be useful for mechanical processing of metallic glasses and additive manufacturing.