Defects activation in CoFe-based metallic glasses during creep deformation

摘要

Maxwell-Voigt model with two Kelvin units and one Maxwell unit was utilized to analyze the microalloying effect of Cu on the creep behavior of CoFe-based metallic glasses at different loading rates.The defect activation during creep deformation was detected by the relaxation time spectrum based on this model.The defect,with respect to a short relaxation time in relaxation spectra,intends to be activated at a quasi-static loading mode in the alloy with 0.5 at.%Cu addition.With further increasing loading rates,more defects with a large size were provoked activated at both hard and soft regions in the Cu-containing sample.A softening with the reduction of elastic modulus and hardness about 10%and 15%,respectively,was also observed in the Cu-doped sample.It is consistent with the pronounced viscoplastic deformation of this alloy along with the decrease of viscosity.Our work provides a microscopic insight into structural evolution during creep deformation in a Cu-doped metallic glass,which might help for understanding the plastic deformation of metallic glasses upon a minor addition.