Measurement of triple junction geometry for extraction of grain boundary energies

A sample of 99.99% aluminum has been rolled and recrystallized to produce an approximately equiaxed grain structure. Serial sectioning was performed in order to measure true dihedral angles and crystal orientations at a large number of triple junctions. The sine law was applied in order to determine the extent to which the grain boundary energy can be approximated by a uniform energy except at small misorientations where the Read-Shockley formula was employed. By calculating a product of assumed boundary energies and sines of associated dihedral angles, an estimate can be made of the validity of the assumed energy distribution. Within the limitations of the scatter, the results indicate that the assumption of uniform boundary energy (except for low angle boundaries) is reasonable.