Sub-Tg relaxation patterns in Cu-based metallic glasses far from equilibrium

We investigate the sub-Tg relaxation patterns (RPs) in binary and quaternary Cu-based glass ribbons (GRs) by using the hyperquenching-sub-Tg annealing-calorimetric approach. This study contributes to revealing the structural or dynamic evolution in liquids related to the observed three-stage sub-Tg relaxation processes in GRs. In this work, we have achieved the following three findings. First, the abnormal three-stage relaxation behavior is not a general phenomenon for Cu-based metallic glasses and could not be simply predicted by the large difference in the enthalpy of mixing between different elements in alloys. Second, the abnormal three-stage RP is associated with the non-monotonic change of cluster size with medium range order in supercooled liquids. Third, the existence of the liquid-liquid phase transition depicted by anomalous viscosity drop during cooling in superheated liquids could be a signature of the unusual structural change causing the abnormal three-step sub-Tg RP in the GRs. This work he...