Relaxation of rapidly quenched metallic glasses: Effect of the relaxation state on the slow low temperature dynamics

The relaxation spectrum of rapidly quenched Mg65Cu25Y10 metallic glass ribbons is studied by mechanical spectroscopy at temperatures below and around the glass transition. The comparison between hyper-quenched and relaxed samples is used to examine the origin of the low temperature “excess wing” of internal friction commonly observed in mechanical spectroscopy of metallic glasses. The results show that the excess wing can be attributed to access of the system to the broad α-relaxation process while evidence of secondary relaxations is not found. This suggests that in this glassy system the activation energies of structural relaxation and low temperature deformation are directly related to the activation energy of the main relaxation process of the glassy state.