  Nanocrystalline materials are defined by their fine grain size, but details
of the grain boundary character distribution should also be important. Grain
boundary character distributions are reported for ball milled, sputter
deposited, and electrodeposited Ni and Ni-based alloys, all with average grain
sizes of ~20 nm, to study the influence of processing route. The two deposited
materials had nearly identical grain boundary character distributions, both
marked by a {\Sigma}3 length percentage of 23-25%. In contrast, the ball milled
material had only 3% {\Sigma}3-type grain boundaries and a large fraction of
low angle boundaries (16%), with the remainder being predominantly random high
angle (73%). These grain boundary character measurements are connected to the
physical events that control their respective processing routes. Consequences
for material properties are also discussed with a focus on nanocrystalline
corrosion. As a whole, the results presented here show that grain boundary
character distribution, which has often been overlooked in nanocrystalline
metals, can vary significantly and influence material properties in profound
ways.
