Calibrating a nanoindenter for very shallow depth indentation using equivalent contact radius

Damir R Tadjiev (1) , Russell J Hand (2) , Simon A Hayes (2)

1 Engineering Materials
2 Engineering Materials

Nanoindenter tips are usually modeled as axisymmetric cones, with calibration involving finding a fitting function relating the contact area to the contact depth. For accurate calibration of shallow depth indentation this is not ideal because it means that deeper indents tend to dominate the fitting function. For an axisymmetric object it is always possible to define an equivalent contact radius (which in the case of nanoindentation is linearly related to the reduced modulus) and to obtain a fitting function relating this equivalent contact radius to indentation depth. The equivalent contact radius approach is used here to provide shallow depth calibration of a nanoindenter tip at three separate times. The advantage of the equivalent contact radius methodology is that it provides a clearer physical interpretation of the changes in tip shape than a conventional area based fit. We also show that the minimum depth for a reliable hardness measurement is obtainable increases as the tip blunts with age but that consistent measurements of very near surface elastic moduli can be made if the blunting of the tip over time is fully accounted for in the tip area function calibration.

Mots clés: Physical Sciences

Damir R Tadjiev, Russell J Hand, Simon A Hayes. Calibrating a nanoindenter for very shallow depth indentation using equivalent contact radius. Philosophical Magazine, 2010, 90 (13), pp.1819-1832. ⟨10.1080/14786430903571420⟩. ⟨hal-00587293⟩