Fatigue behavior of Cu-Zr metallic glasses under cyclic loading

TL;DR

This study uses molecular dynamics simulations to explore how cyclic shear deformation affects fatigue life, yielding, and flow localization in Cu-Zr metallic glasses, revealing critical strain amplitudes and failure behaviors.

Contribution

It provides new insights into fatigue mechanisms in metallic glasses under cyclic loading, highlighting the role of strain amplitude and localization phenomena.

Findings

Plastic events are highly localized below critical strain amplitude.

Above the critical strain, shear bands form and lead to failure.

Number of cycles to failure follows a power-law near the critical point.

Abstract

The effect of oscillatory shear deformation on the fatigue life, yielding transition, and flow localization in metallic glasses is investigated using molecular dynamics simulations. We study a well-annealed Cu-Zr amorphous alloy subjected to periodic shear at room temperature. We find that upon loading for hundreds of cycles at strain amplitudes just below a critical value, the potential energy at zero strain remains nearly constant and plastic events are highly localized. By contrast, at strain amplitudes above the critical point, the plastic deformation is gradually accumulated upon continued loading until the yielding transition and the formation of a shear band across the entire system. Interestingly, when the strain amplitude approaches the critical value from above, the number of cycles to failure increases as a power-law function, which is consistent with the previous results on binary Lennard-Jones glasses.