Rejuvenation behaviors of recovery-annealed Cu–Zr metallic glass with different thermal treatment conditions: a molecular dynamics study

Abstract

The recovery annealing process, which reheats the relaxed metallic glass (MG) to a certain temperature above glass transition temperature and subsequently rapid quenched, could tailor the sample to a less relaxed state, called as rejuvenation process. During the recovery annealing process, the final cooling rate, isothermal time and annealing temperature all affect the obtained rejuvenated state. In the present study, we investigated the changes of configurational potential energy and atomic structure of Cu–Zr MG under various different parameters by using molecular dynamics simulation. We found that when the final cooling rate after recovery annealing exceeds the cooling rate of the as-cast sample, a transition point from ageing to rejuvenation exists in the annealing temperature ranging from 900 to 1000 K. Meanwhile, the degree of ageing when annealed at 900 K, as well as the degree of rejuvenation when annealed at 1000 K, improves with a longer isothermal time. The transition behavior from ageing to rejuvenation at different annealing temperatures is mainly caused by the variation of proportions of Cu-centered and Zr-centered polyhedra in the supercooled liquid region. This work provides a profound understanding of the change in configurational potential energy and atomic structure during recovery annealing with different thermal parameters.