  Grain boundary networks should play a dominant role in determining the
mechanical properties of nanocrystalline metals. However, these networks are
difficult to characterize and their response to deformation is incompletely
understood. In this work, we study the grain boundary network of
nanocrystalline Ni and explore whether it can be modified by plastic
deformation. Mechanical cycling at room temperature did not lead to structural
evolution, but elevated temperature cycling did alter the grain boundary
network. In addition to mechanically-driven grain growth, mechanical cycling at
100 $\deg$C led to a 48% increase in $\Sigma$3 boundaries, determined with
transmission Kikuchi diffraction. The extent of boundary modification was a
function of the number of applied loading cycles and the testing temperature,
with more cycles at higher temperatures leading to more special grain
boundaries. The results presented here suggest a path to grain boundary
engineering in nanocrystalline materials.
