Stokes-Einstein relation in dense metallic glass-forming melts

Quasielastic neutron scattering has been used to investigate atomic motion in a very fragile binary metallic melt and a multicomponent bulk glass-forming metallic melt. Both melts show a breakdown of the Stokes-Einstein relation and display a change in the slope of In D dependence on In ( η / T ) . We also observed that the values for the exponent in the fractional Stokes-Einstein relation are not in the commonly observed range for Cu 46 Zr 42 Al 7 Y 5 melts. At low temperatures, the deviation from the Stokes-Einstein law is very significant and can be expressed in the form of a power law with exponent ξ = − 1.82 ± 0.08 . The change in the slope is found to be associated with a change in friction coefficient while increasing the packing density of the melt. The abrupt change in the value of friction coefficient is independent of packing density, but it occurs at a common value of ζ = ( 3.2 ± 0.1 ) × 10 − 12 kg s − 1 in these melts.