Signature of viscous flow units in apparent elastic regime of metallic glasses

We characterize and identify the flow units in two typical metallic glasses (MGs), which have markedly different beta-relaxation behaviors and mechanical properties. The viscoelastic hysteresis loops are found in the cyclic deformation in the nominal elastic regime of the metallic glasses. We show that the hysteresis loops are related to the activation of the flow units in metallic glasses, and a model is proposed to describe the flow units. We demonstrate that the flow units are both the deformation units of the anelastic and plastic deformation behaviors and the structural origin of the beta-relaxation in metallic glasses. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4753813]