| Abstract Scope |
Metallic glasses can exist in many structural states, with variable properties. While the fictive temperature or enthalpy are useful parameters that describe those states, they don’t describe them uniquely. At the same fictive temperature, different behavior, e.g., enthalpy, deformation or magnetic properties, is observed. Using anelastic relaxation measurements over ~10 orders of magnitude of time, we obtain time constant spectra, which contain a wealth of information. They contain distinct peaks, fitted well by a model of thermally activated shear transformation zones, exhibiting a quantized hierarchy of shear transformation zones (STZs). Both alpha and beta relaxation are part of this hierarchy, but correspond to different nanoscale domains or different local STZ compositions. Furthermore, in contrast to common assertions, the alpha relaxation is not intrinsically irreversible – rather, it is fully reversible at small strain. The results will be used to provide microscopic descriptions of rejuvenation and plasticity.
Funding: NSF Grant DMR-1708043 |