  Addition of solutes is commonly used to stabilize nanocrystalline materials
against grain growth. However, segregating at grain boundaries, these solutes
also affect the process of dislocation nucleation from grain boundaries under
applied stress. Using atomistic simulations we demonstrate that the effect of
solutes on the dislocation nucleation strongly depends on the distribution of
solutes at the grain boundary, which can vary dramatically depending on the
solute type. In particular, our results indicate that the solutes with a
smaller size mismatch can be more effective in suppressing dislocation emission
from grain boundaries. Bearing in mind that dislocation slip originating from
grain boundaries or their triple junctions is the dominant mechanism of plastic
deformation when grain sizes are reduced to the nanoscale, we emphasize the
importance of the search for the optimal solute additions, which would
stabilize the nanocrystalline material against grain growth and, at the same
time, effectively suppress the dislocation nucleation from the grain
boundaries.
