Atomistic simulation of twin boundaries effect on nanoindentation of Ag(1 1 1) films

Atomistic simulations were employed to study the effect of a single twin boundary parallel with the indented surface on nanoindentation of Ag(1 1 1) films. The results show that the twin boundary has little influence on the elastic modulus of films. The load for the initial yield is observably reduced when the twin boundary is very near the indented surface due to the nucleation of the glissile dislocations on the slip plane parallel to the surface, rather than the formation of the tetrahedral sessile lock when nanoindentation on the perfect film. Twin boundaries are effective obstacles to the motion of dislocations, and change the dislocation patterns dominating the deformation, resulting in the hardening of films. In addition, twin boundaries can act as dislocation sources before losing their coherency.