Connectivity of CSL grain boundaries and the role of deviations from exact coincidence

The practical classification of grain boundaries as coincidence site lattice (CSL) boundaries requires the use of an acceptance criterion, of which the classical Brandon criterion is the most commonly used. In this work, we consider the role of the acceptance criterion on the grain boundary character distribution, triple junction distribution, and the boundary clustering behavior in nine experimental microstructures. The Brandon criterion is directly compared with the Palumbo-Aust criterion, which is more restrictive in the allowable deviations from exact CSL misorientation. Although the latter criterion causes changes in the CSL fraction, the triple junction distributions, and the cluster characteristics of the experimental microstructures, these changes are all mutually commensurate. The essential features of boundary connectivity are therefore not fundamentally affected by the choice of a CSL acceptance criterion.