COMBINING SCANNING FORCE MICROSCOPY WITH NANOINDENTATION FOR MORE COMPLETE CHARACTERIZATION OF BULK AND COATED MATERIALS

The mechanical properties of thin films as well as bulk materials can be measured by a variety of different techniques, with nanoindentation being one of the most recent developments in this growing field. By u sing a depth-sensing indentation method it is possible to obtain quant itative values for the hardness and modulus, and thus gain better insi ght into the response of a material to controlled deformation at such small scales. However, the calculation of such values from conventiona l load-displacement curves can prove inaccurate owing to the effects o f pile-up and sink-in which invariably occur during the indentation of many types of material and which seriously affect the calculation of residual contact area. This paper addresses the problem and suggests t he use of scanning force microscopy (SFM) as a complimentary tool whic h allows the true residual contact area to be measured. In addition, s ome experimental results are presented for a variety of bulk and coate d materials, these confirming the use of the SFM for obtaining signifi cant additional information concerning the true response of a material to instrumented indentation at a nanometric scale, e.g., elastic/plas tic deformation, cracking, phase transformation, pile-up/sink-in effec ts, etc. (C) 1998 Elsevier Science S.A. All rights reserved.