Determination of absolute solid-liquid interfacial free energies in metals

Abstract A method is described for determining absolute values for the solid-liquid interfacial free energy γSL in metals. This technique depends on the equilibrium established at the intersection of a low-angle grain boundary with the solid-liquid interface. The variation with boundary misorientation of the dihedral angle at the root of a tilt-boundary groove is shown theoretically to depend on γSL in a simple manner. Data obtained from electron microscopy studies of solid-liquid interfacial grooves in pure bismuth, and then analyzed with the theory developed here, yield a value for γSL = 61.3 erg/cm2—in substantial agreement with, but about 15% larger than, the value obtained from homogeneous nucleation experiments. The influence of various factors usually neglected in homogeneous nucleation theory, such as anisotropy in γSL , interface diffuseness, interface extensiveness, etc., are interpreted in the light of the independent determination of the interfacial free energy. Limitations and possible pitfalls in applying the new method are discussed in considerable detail.

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