Temperature-dependent surface tension of critical nucleus in crystal-melt nucleation

Using the previously developed order-parameter model of liquid-solid nucleation of bce elements [J. Phys. Soc. Jpn. 65 (1996) 2311], we calculate various thermodynamic functions of liquid-solid interface and the temperature dependence of the effective surface tension of critical nuclei in supercooled liquid metals. The results are compared with the diffuse interface model of Spaepen [Solid State Physics 47 (1994)1] and Granasy [J. Non-Cryst. Solids 162 (1993) 301]. It is shown that the assumption made in the diffuse interface model is qualitatively correct in the order-parameter model. However, the temperature coefficient of the effective surface tension becomes positive in the diffuse interface model, while it becomes negative in the order-parameter model. It is suggested that the temperature dependence is determined from a delicate balance of the interfacial entropy and the entropy of fusion.