Atomic dynamics of metallic glass melts La50Ni15Al35 and Ce70Cu19Al11 studied by quasielastic neutron scattering

By employing quasielastic neutron scattering, we studied the atomic-scale relaxation dynamics and transport mechanism of La50Ni15Al35 and Ce70Cu19Al11 metallic glass melts in the temperature range of >200K above their liquidus temperatures. The results show that both liquids exhibit stretched exponential relaxation and Arrhenius-type temperature dependence of the effective diffusion coefficient. The La50Ni15Al35 melt exhibits an activation energy of 0.545 ± 0.008 eV and a stretching exponent ∼0.77 to 0.86 in the studied temperature range; no change of activation energy, as suggested in previous reports, associated with liquid-liquid phase transition was observed. In contrast, the Ce70Cu19Al11 melt exhibits larger diffusivity with a much smaller activation energy of 0.201±0.003eV and a smaller stretching exponent ∼0.51 to 0.60, suggestive of more heterogeneous dynamics.