Reaching theoretical strengths in nanocrystalline Cu by grain boundary doping

The yield strength of dilute nc-Cu alloys was investigated using molecular dynamics simulations. Alloying additions that lower grain boundary energy were found to dramatically increase the yield strength of the alloy, with dilute Cu–Nb alloys approaching the theoretical strength of Cu. These findings suggest a new scaling behavior for the onset of plasticity in nanocrystalline materials, one that depends on the product of the specific grain boundary energy and molar fraction of grain boundary atoms, and not simply on grain size alone.