Influence of tip bluntness on the size-dependent nanoindentation hardness

Nanoindenter tip bluntness modifies the size-dependent hardness relationship given by the Nix-Gao model. At shallow depths, fewer geometrically necessary dislocations are needed to accommodate the blunted tip. The experimentally measured ratio of plastic to total contact depth decreases and the hardness decreases relative to the idealized Nix-Gao model.