Improving grain boundary sliding resistance with segregated dopants

Molecular dynamics simulations are used to study GB sliding in pure and doped Cu bicrystals using both Lennard-Jones and Embedded-Atom Method potentials. Two tilt [1 0 0] grain boundaries are considered: the coincident site lattice Σ5 (3 1 0) interface and an incoherent high angle interface. Shear stress between 0.69 and 1.61 GPa was applied to the bicrystals at ambient temperature (300 K) and high temperature (800 K). Without dopants, the Σ5 interface slide more than the random interface at 300 K and less at 800 K. We observe that the structural unit of the Σ5 boundary promotes atomic shuffling at low temperatures, in agreement with [F. Sansoz, J.F. Molinari, Acta Mater. 53 (2005) 1931]. For the doped bicrystals, interstitial dopants and oversized substitutional dopants were effective in retarding GB sliding. These simulations will aid further work to determine how segregated dopants can alter, and possibly improve, the tensile properties of nanocrystalline metals.