Depth-Dependent Hardness Characterization by Nanoindentation using a Berkovich Indenter with a Rounded Tip

Abstract

The height difference Δh_b between the ideally sharp Berkovich indenter tip and a Δh_b rounded tip was measured by direct observation using atomic force microscopy (AFM). The accuracy of the indirect area function method for measuring h was confirmed. The Δh_b indentation size effects (ISE) in (100) single crystal copper, (100) single crystal tungsten, and fused quartz were characterized by applying the ISE model considering the rounded tip effect. The model fits the data these materials well, even though fused quartz does not deform by dislocations. However, a very small value of the ISE characteristic length h’ was obtained for fused quartz. The present h’ value for (100) copper is 32% larger than a previously-measured value for polycrystalline copper. This may indicate that grain boundaries suppress the dislocation activity envisioned in the ISE model.