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- Calibration (1)
- Indentation area (1)
- Indentation hardness (1)
- Indentation modulus (1)
- Indenter area function (1)
- Instrument compliance (1)
- Nanoindentation (1)
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The accuracy and comparability of nanoindentation results depend significantly on the calibration of area function and instrument compliance. The area function results should not depend on the reference material used or on the calibration method (direct or indirect). This has been investigated for 18 different Berkovich tips. A novel calibration method is proposed that confirms the material independence of the area function and gives a force-dependent instrument compliance function. An agreement between direct and indirect calibration could only be achieved by considering a radial displacement correction. Further, it is shown that the transition range from a spherical cap to the correct face angle of the pyramid can extend to a depth of more than 250 nm. A better parameter for the indenter than the tip radius is the offset of the contact radius to the radius of an ideal tip at a depth where the correct face angle is reached.
An extensive comparison between the conventional Vickers hardness at 500 mN and indentation hardness measured with Vickers indenters at 500 mN is presented for up to 20 different materials and for three different instruments. Additionally, the indentation modulus is compared to Young’s modulus, which was measured with alternative methods or taken from the literature. It is shown that the agreement between the results from depth-sensing indentation and the reference values can be improved by additional corrections, for the calculation of the indentation area. With corrections the mean hardness difference to the Vickers hardness reference as average of all investigated materials can be reduced to about 10 % although disturbing pile-up or sink-in effects can still not be considered. For the modulus, the mean difference was only about 6 %.