Abstract
This study aims to establish a simple predicting method for impurity diffusion coefficients of elements, including the effect of atomic weight in liquid Sn based on a hard-sphere model. The impurity diffusion coefficients of Al, Au, and Cu in liquid Sn at 573 K were measured using the shear cell technique and stable density layering. Furthermore, we proposed different prediction methods for impurity diffusion coefficients of elements using a multiple regression analysis based on (σSn/σi)ϕis, where σi and ϕis are atomic diameter and thermodynamic factor of solute element i in solvent element s, respectively. Impurity diffusion coefficients of elements, the value (σSn/σi)ϕis of which is approximately 1.2 or small in liquid Sn near the melting point, were simply proportional to the product of the following three factors with the self-diffusion coefficient of Sn as the slope: (i) the atomic diameter ratio of Sn to the solute element, (ii) 0.182 power of the reduced mass ratio of Sn to the solute element, and (iii) thermodynamic factor. The uncertainty of the impurity diffusion coefficients of reference values and Al was within 6%. However, the impurity diffusion coefficients of elements, the value (σSn/σi)ϕis of which is approximately 1.2 or large, were approximately equal to the self-diffusion coefficient of Sn. This was owing to the inhibited atomic diffusion of Au and Cu in liquid Sn.
