Diffusion and viscosity in molten Pd40Ni40P20 and Pd40Cu30Ni10P20 alloys

The self diffusion of Ni-62 and the shear viscosity in liquid Pd40Ni40P20 and Pd40Cu30Ni10P20 have been measured. The used methods were the long-capillary technique for diffusion measurement and the gas-film-levitation for viscosity measurement. The temperature dependence of diffusion in the equilibrium melt follows the prediction of the mode-coupling theory. The Stokes-Einstein relation describes well the momentum and mass transport in both melts. The Ni-62 diffusion is equal in both alloys whereas the normalized bulk viscosity is higher in Pd40Cu30Ni10P20. Thermodynamic and structural considerations are invoked to propose a qualitative explanation for this behavior. (C) 2004 Elsevier B.V. All rights reserved.