Plasticity initiation and evolution during nanoindentation of an iron-3% silicon crystal.

Our investigations confirm that the collective, avalanchelike dislocation nucleation and multiplication is responsible for the pop-in event in a body-centered-cubic Fe-3% Si single crystal. Dislocation was not observed prior to pop-in but was apparent after the event. We find that a transition from an initial stage dominated by discrete dislocation nucleation to subsequent continuum plasticity occurs just after the pop-in event as elastoplastic deformation ensues.