Abstract Scope |
Structural relaxation is often considered to be a continuous process characterized by steadily increasing relaxation times. However, recent literature shows distinct intermittent aging events. Here, we shed light onto long-time aging signatures of a Zr-based bulk metallic glass at 0.98Tg using x-ray photon correlation spectroscopy (XPCS). Probed over the duration of eight individual experiments of ca. 35000 s each, we reveal temporal fluctuations of all extracted quantities, including the short-time plateau, the first moment in time, the relaxation time, and the shape parameter. Whilst strong fluctuations of any investigated parameter may appear as a rare event in an individual two-time correlation function, variations over larger timescales emerge as the norm, which emphasizes the time-scale interplay between an experimental time and a broad distribution of material timescales. This suggests that aging close to or below Tg is generally a temporally heterogeneous process, if sufficiently sampled in time. |