We use coherent x rays to probe the aging dynamics of a metallic glass directly on the atomic level. Contrary to the common assumption of a steady slowing down of the dynamics usually observed in macroscopic studies, we show that the structural relaxation processes underlying aging in this metallic glass are intermittent and highly heterogeneous at the atomic scale. Moreover, physical aging is triggered by cooperative atomic rearrangements, driven by the relaxation of internal stresses. The rich diversity of this behavior reflects a complex energy landscape, giving rise to a unique type of glassy-state dynamics.

For a metallic glass, vitrification kinetics takes place at temperatures lower than expected from the α-relaxation.

The thermodynamic functions of the bulk metallic glass (BMG) forming ${\text{Pd}}_{43}{\text{Ni}}_{10}{\text{Cu}}_{27}{\text{P}}_{20}$ alloy are determined calorimetrically as a function of temperature. Along with eight other BMG forming alloys, the available experimental thermodynamic and viscosity data are reassessed. For each alloy, consistent Vogel–Fulcher–Tammann (VFT) fits of the viscosity measurements are established, and the temperature dependence of the configurational entropy is calculated from thermodynamic data. Together with the VFT fits, fits to the Adam–Gibbs equation are performed using this configurational entropy change. We find remarkable agreement between the Adam–Gibbs and VFT fits. Moreover, the temperature $T_0$ is obtained from the VFT fits at which the viscous flow diverges. This $T_0$ matches very well the temperature where the configurational entropy vanishes in the corresponding Adam–Gibbs fits.