Examination of Berkovich indenter tip bluntness

• Bluntness of Berkovich indenter examined throughout the period of two years using AFM and indirect analyses.
• Estimation of equivalent radius of spherical part depends on indenter state and analysis employed.
• Equivalent radius of spherical part of Berkovich indenter increases with depth of penetration.
• Proposed methods are suitable for monitoring of the indenter wear.

Actual shape of the indenter is very important parameter affecting the results and interpretation of nanoindentation tests. In this study, bluntness of the tip was determined by direct (atomic force microscopy) and indirect methods (indentation into reference materials) for different states of the indenter over its lifetime. It was found that the equivalent radius depends on the used analysis method. Moreover, equivalent radius changes with the distance from indenter apex. Axisymmetric 2D sphero-conical and 3D finite element models of the indenter geometry were used to predict force-displacement curves which we