Strain-induced coarsening in nano-grained films

The potential use of nanostructured materials in structural applications is severely restricted by their low ductility, which due to a limited capacity for work-hardening. Since nanograin size eliminates the dislocation-dislocation interactions that ordinarily control work-hardening, new hardening mechanisms must be identified and exploited if this problem is to be overcome. One possible approach to controlling work hardening is to exploit strain-induced reconfiguration or coarsening of the grains themselves. In the present work, we discuss recent observations of mechanically induced grain coarsening during the nanoindentation of micro-grained and nanograined aluminum. These phenomena are studied directly through in situ nanoindentation in an electron microscope.