Examination of Berkovich indenter tip bluntness

• Published in: Materials & design 2016-11, Vol.109, p.347-353
• Main Authors: Čech, Jaroslav, Haušild, Petr, Kovářík, Ondřej, Materna, Aleš
• Format: Article
• Language: English
• Subjects: Actual indenter shape; Axisymmetric; Equivalence; Force-displacement curves; Indenters; Mathematical models; Nanoindentation; Three dimensional models; Tip blunting; Two dimensional
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2016.07.033

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 were compared with experiment. It was shown, that there exists a significant difference between 2D and 3D models caused by the simplifications of actual 3D shape of Berkovich indenter by sphero-conical model. The sphero-conical model can serve as good estimator of indenter bluntness and it is convenient for the description of the indenter wear throughout its lifetime. [Display omitted] •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.