The method of zero creep, utilizing the concept of balance of surface tension in thin wires and observations of twin-boundary/grain-boundary intersections in thin foils, were used to measure absolute (average) interfacial free energies in Ni-20Cr (Chromel-A) at 1060C. By using optical microscopy and scanning electron microscopy to measure equilibrium grain lengths and wire diameters, and transmission electron (projection shadowgraph) microscopy to accurately determine the dihedral angles at the intersection of grain boundaries with the wire surface, the surface and grain-boundary free energies were measured to be 1960 and 680mJ/m2, respectively. From measurements of a representative number of low-torque twin-grain boundary intersections in thin foils using transmission electron microscopy, the twin boundary free energy was calculated to be 17mJ/m2 from a relative twin/grain boundary free energy ratio of 0.025.

Measurement of Absolute Interfacial Free Energies in a NiCr Alloy. L.E.Murr, R.J.Horylev, G.I.Wong: Surface Science, 1971, 26[1], 184-96