Novel nanoindentation method for characterising multiphase materials

We present the nano-hardness tester (NHT), a new depth-sensing instrument with a differential capacitive sensor providing nanometer depth resolution and allowing partial elimination of the frame compliance. With micron lateral positioning of the sample and topographical measurement of the residual indent, using scanning force microscopy, it is possible to gain a better understanding of the indentation method and its effects on the material being tested. Furthermore, parallel imaging allows the material response to be directly investigated. Experimental results are presented for a selection of aged austeno-ferritic stainless steels; these confirm the ability of the NHT to become a common test instrument in quality assurance and process development of multiphase materials. (C) 1997 Elsevier Science S.A.