  Solid solution effects on the strength of the finest nanocrystalline grain
sizes are studied with molecular dynamics simulations of different Cu-based
alloys. We find evidence of both solid solution strengthening and softening,
with trends in strength controlled by how alloying affects the elastic modulus
of the material. This behavior is consistent with a shift to collective grain
boundary deformation physics, and provides a link between the mechanical
behavior of very fine-grained nanocrystalline metals and metallic glasses.
