Spherical indentation of copper: Crystal plasticity vs experiment

We analyse spherical nanoindentation of single crystal copper using two different indenter tips of radii 7.4 and 27 mu m. The surface deformation surrounding the indents was measured using atomic force microscopy and the elastic rotation fields under the indents were measured using electron diffraction and transmission techniques. Using the measured load-displacement, surface relief, plastic zone size, and elastic rotation field removed the ambiguity in the optimal slip and hardening law parameters in a three parameter strain gradient crystal plasticity model. In addition to geometrically necessary dislocations, other hardening mechanisms were found to contribute to the size effect.