Instrumented Indentation Test in the Nano-range: Performances Comparison of Testing Machines Calibration Methods

In the modern manufacturing industry, dealing with innovative productions and advanced materials, technological surface characterisation is becoming crucial to qualify components and optimise processes. Instrumented indentation test is an effective method for characterising mechanical behaviour of materials through the analysis of the force–displacement curve obtained during the implementation of a predefined loading/unloading cycle. Instrumented indentation test allows for hardness test to be performed at different force ranges, thus enabling bulk to local material characterisation. To guarantee the characterisation accuracy, rigorous procedures for the calibration of testing machines are defined in ISO 14577-2. In particular, calibration of frame compliance and indenter area function may be addressed according to methods which do not require the indenter area function to be known a priori, thus avoiding the need of high-resolution microscopes. The present work aims at comparing performances and compatibility of these methodologies by considering tests performed in the nano-range.