Formation sequences and roles of multiple deformation twins during the plastic deformation in nanocrystalline fcc metals

Large-scale molecular dynamics (MD) simulations were performed to investigate the tensile plastic deformation of nanocrystalline Ag. With increasing tensile strain, formation of SFs, single deformation twins, V-shaped and T-shaped double twins, and 5-fold twins successively starts to play a role on the plastic deformation of nanocrystalline Ag. The direct evidences of the formation sequences for the following two twinning mechanisms are presented in the present study: GB-mediated intersecting mechanism and self-partial-multiplication twinning mechanism. Moreover, the 5-fold twins are found to be formed by a combination of these two mechanisms. The findings in the present study contribute to the understanding of formation mechanisms and roles of multiple twins on the plastic deformation of nanocrystalline fcc metals with low stacking fault energy.