Diffusion and viscosity in molten Pd40Ni40P20 and Pd40Cu30Ni10P20 alloys

The self diffusion of 62Ni 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 62Ni 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.