Rejuvenation-deformation relationship of a well-aged metallic glass during Newtonian to non-Newtonian flow

Stress overshoot is a sign of structural rejuvenation of metallic glass, which usually occurs in non-Newtonian flow with large strain rate. Here we show a heavily-aged Zr-based metallic glass that rejuvenates by low-strain-rate Newtonian flow without showing any stress overshoot. Its rejuvenation does not increase the energy level of its basin of potential energy landscape, but reduces the basin`s mechanical stability. Synchrotron X-ray total scattering gives direct evidence that under Newtonian flow, the rejuvenation is contributed by complex structural rearrangements over short- and medium-range order scales. We further find that due to the structurally inhomogeneous response, there is an optimal strain rate for rejuvenation, above which the energy level decreases, but the characteristic size of the medium-range order continues to increase. Thus, the mechanical stability and structural disorder do not decrease synchronously. Our findings refresh the understanding of the relationship between mechanical deformation and structural rejuvenation in metallic glasses.