Abstract
In order to clarify the relative importance of various factors for the solute diffusion, the diffusion coefficients of Cu, Ag and Au in liquid copper and silver have been measured by using the capillary reservoir method in the temperature range 1100 to 1300°C. The results obtained in the current investigation are summarized as follows:
(1) In liquid copper, the diffusivity increases as the radius and the mass of diffusing particle decrease. On the other hand, the difference between the diffusivities of the solutes and the solvent in liquid silver is not so significant as in the case of liquid copper. This may be caused by the small degree of the viscosity and the large free volume of liquid silver.
(2) The activation energies of solutes having the solute-solvent binding energy higher (or lower) than the solvent-solvent binding energy are lower (or higher) than that of solvent self diffusion.
(3) Applicability of the critical free volume and the microfluctuation theories have been examined on the basis of the results obtained. It is shown that the diffusion theories are improved by taking account of the mass effect, the size effect and the solute-solvent binding energy, respectively.
