Twinning from Triple Lines in Nanocrystalline Copper by Molecular Dynamics Simulation

As the intersecting line of three grain boundaries (GBs), triple line possesses large stress concentration and extra energy, which makes it the optimal nucleation site for twin embryos. In present work, molecular dynamics (MD) simulation on nanocrystalline Cu indicated that 27 out of 28 twins were emitted from triple lines. Stress relaxation and energy reduction were considered to be the driving force for twinning from triple lines. This could be proved by changes of dihedral angles, relative GB energy sum, average atomic von Mises shear stress and average atomic energy.