Unexpected creep behavior in a rejuvenated metallic glass

Rejuvenation, bringing metallic glasses (MGs) to the younger and higher energy states, provides an alter-native avenue to explore the interplay between the property and microstructures of MGs. In this study, the creep behavior of the Zr69.5Cu12Ni11Al7.5 MGs was experimentally examined by controlling the en-ergy state in terms of structural rejuvenation and thermal annealing. It is found that compared to the as-cast counterpart, the annealed MG at a lower energy state exhibits a higher hardness, a smaller dis-placement, and a lower creep rate due to the decreased free volume and the inhibited activation of the shear transformation zone. Conversely, the rejuvenated MG at a high energy state displays lower hardness and increased free volume content, yet it demonstrates superior creep resistance compared to its as-cast counterpart, which deviates from conventional understanding. This unexpected phenomenon occurs as the initial high-content free volume annihilates during creep, and strain hardening takes precedence over strain softening as the prevailing process during creep deformation, leading to a superior creep perfor-mance in extremely rejuvenated MGs.& COPY; 2023 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

Rejuvenation provides an alternative avenue to explore the relationship between property and microstructures of metallic glasses (MGs). This study experimentally examines the creep behavior of Zr69.5Cu12Ni11Al7.5 MGs by controlling the energy state through structural rejuvenation and thermal annealing. The findings reveal that the annealed MG at a lower energy state exhibits higher hardness, smaller displacement, and lower creep rate, while the rejuvenated MG at a high energy state displays lower hardness and increased free volume content but demonstrates superior creep resistance.