  The grain boundary-mediated mechanisms that control plastic deformation of
nanocrystalline metals should cause evolution of the grain boundary network,
since they directly alter misorientation relationships between crystals.
Unfortunately, current experimental techniques are unable to track such
evolution, due to limits on both spatial and temporal resolution. In this work,
molecular dynamics simulations are used to study grain boundary restructuring
in nanocrystalline Al during both monotonic tension and cyclic loading. This
task is enabled by the creation of new analysis tools for atomistic datasets
that allow for a complete characterization and tracking of microstructural
descriptors of the grain boundary network. Quantitative measurements of grain
boundary character distribution, triple junction type, grain boundary plane
normal, and other interfacial network characteristics are extracted and
analyzed. The results presented here show that nanocrystalline plasticity leads
to an increase in special boundary fraction and disruption of two-dimensional
boundary connectivity, with the most dramatic evolution occurring in the
smallest grain sizes.
