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

TL;DR

This study uses molecular dynamics simulations to show that small-amplitude oscillatory shear can heal shear bands in amorphous materials, improving their mechanical properties through cyclic loading.

Contribution

It demonstrates that cyclic shear deformation can effectively anneal shear bands and enhance mechanical strength in binary glasses, a novel approach for material processing.

Findings

Shear bands are relocated to deeper potential energy states with increasing strain amplitude.

Shear modulus and yield stress increase during cyclic loading, especially near the yield strain.

Shear band clusters decay over time, leading to reversible elastic 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.