The solid–liquid interface free-energy of Pb: comparison of theory and experiments

Abstract

The solid–liquid interface free-energy γsl is a key parameter controlling nucleation and growth during solidification and other phenomena. Different experimental techniques are available for its evaluation but results are often widely scattered and strongly depend on the technique used. One of the best examples in this sense is the case of elemental Pb, with values for γsl differing by as much as 150% between nucleation rate experiments and contact angle data. Even using simple many-body potentials, theoretical calculations of γsl can exceed this level of accuracy and thus be employed to assess the present experimental data. To this purpose, atomistic calculations are performed in conjunction with two different many-body potentials for Pb. These show good agreement with nucleation rate and depression of melting point experiments and support the case for a reassessment of the measurements reported from contact angle data. Possible sources of errors that might have affected these experiments are critically discussed, showing how the magnitude of the anisotropy in the interfacial free energies can be important in closing the gap between the different sets of experimental data.