USING NEW ATOMIC FORCE MICROSCOPE SOFTWARE TO MEASURE THE HARDNESS OF GRAINS AND MICROCONSTITUENTS

Abstract- It is desirable to measure the hardness of individual grains and microconstituents to have control over the mechanical properties of materials. An ultra-micro or nanoindenter is required to make indents small enough to fit inside a single grain or phases that is smaller than 10 mm diameter. Because the indents are too small for an optical microscope an atomic force microscope was used to view the location and measure the contact area. Measuring the contact area of indents from an atomic force microscope image is unreliable because it is difficult to manually locate the indent edge. To solve this problem computerized image analysis software called NanoMc was used to measure the residual indent contact area. This software digitally reconstructed the residual indent back into the fully loaded indentation shape and then measures the contact area and depth. This method avoids the complicated tip rounding and load-frame compliance problems. As an example this method was used to measure the hardness of pearlite and ferrite microconstituents in SAE 1020 steel