LOCALIZED MICRO-HARDNESS MEASUREMENTS WITH A COMBINED SCANNING FORCE MICROSCOPE NANOINDENTATION SYSTEM/

Thin-film coatings, modified surface layers and multiple phases are in creasingly being used to improve the properties and functionality of e ngineering materials. Nanoindentation effectively meets the industrial need to measure hardness on a micro- and even nanometre scale and has proved its worth in characterising the mechanical properties of surfa ces, subsurface regions, interfaces, phases and grain boundaries in a quasi non-destructive way. The depth-sensing indentation method provid es a means of evaluating the elastic and plastic deformations of the t ested material, from which the hardness and the elastic modulus can be calculated. The combination of such an instrument with high resolutio n scanning force microscopy (SFM) and a conventional optical microscop e provides a system capable of a more complete analysis of important s urface parameters such as surface micro-roughness, topography and grai n structure. in addition to the precise measurement of the indentation depth, the displaced material volume can also be measured together wi th other important information concerning the processes taking place o n a microscale whilst performing such an indentation, e.g. plastic flo w, micro-fracture, material compression and other interfacial effects. First results obtained on a multiphase high speed steel are presented , showing the net advantages of such a system in carrying out highly l ocalised indentation studies together with precise measurement of impr ints via SFM.