Role of low melting point element Ga in pronounced β-relaxation behaviors in LaGa-based metallic glasses

In contrast to most metallic glasses (MGs) which exhibit weak beta-relaxation peak in their dynamic mechanical spectra, the LaGa-based MGs we report here show a distinct beta-relaxation peak with the ratio of beta/alpha-relaxation peaks up to similar to 0.32 in the mechanical relaxation measurements. Moreover, the beta-relaxation behavior can be tuned by modification of the chemical composition and the concentration of flow units. The effects of gallium and structural origin of the beta-relaxation in the MGs have been discussed. The LaGa-based MGs with pronounced slow beta-relaxation could provide a model system to investigate some underlying issues of the relaxation and plastic mechanism of MGs. (C) 2015 AIP Publishing LLC.