Triple-junction morphology classification and dihedral angle distribution during 2D grain growth

We analyzed and classified the grain structure in the vicinity of triple junctions during an ideal 2D grain growth process. We used the multi-order parameter phase-field grain-growth model to generate the grain structures and evaluated the distribution of the dihedral angles between the grain boundaries at triple junctions. The triple junctions were classified based on the microstructure represented by the sharp-interface representation, and the dihedral angles were estimated using the angle between the gradient of the order parameters. The average value was 120 degrees. We also observed that the peak position of the angle distribution was less than 120 degrees. However, the distributions of the three most frequent major classes showed a peak at 120 degrees or a plateau region between 110 degrees and 130 degrees. These observations are explained on the basis of force-balance analysis at the triple junctions.