It was recalled that the well-known σ combination rule governed the connectivity of coincidence site lattice grain boundaries at triple junctions, but was strictly applicable only to ideal coincidence site lattice boundaries. This relationship was extended here to boundaries that deviated from ideal coincidence site lattice misorientations, and derive a complementary rule that relates their angular deviations. This “deviation limit rule” states that the angular deviation of one boundary at a triple junction was at most equal to the sum of the other two deviation angles. This analysis also provided insight into apparent violations of the sigma combination rule, which could arise when one boundary deviates beyond the allowable limit for coincidence site lattice classification.

Combination Rule for Deviant CSL Grain Boundaries at Triple Junctions. M.Frary, C.A.Schuh: Acta Materialia, 2003, 51[13], 3731-43