Evaluation of mechanical properties in nanometer scale using AFM-based nanoindentation tester

A nanoindentation hardness tester was developed on the basis of an atomic force microscope (AFM) to evaluate mechanical properties of microstructures. Not only the force penetration depth curves but the topographic images can be obtained by this tester One of new features of the developed tester was modified lever design in order to accommodate the Berkovich indenter into the middle of the level: Furthermore, a piezo-actuator was added to control the applied force and the vertical displacement of the lever was monitored by a laser displacement detector The diamond tip works as both an AFM tip and indenter. Force - penetration depth curves represent mechanical properties of specimens. However because of indentation size effect the hardness values obtained by nanoindentation testers are usually greater than the bulk hardness. In this paper several metallic single crystals were used as standard specimens and an empirical model for calculating Vickers hardness from force penetration depth curves is proposed. Finally, mechanical properties of ferrite in pearlitic steels were obtained using the instrument. (C) 1999 Acta Metallurgica Inc.