NANOHARDNESS MEASUREMENTS FOR STUDYING LOCAL MECHANICAL-PROPERTIES OFMETALS

Studying local mechanical properties of metallic alloys and composites and their defect structures such as grain boundaries, cracks, and dis locations allows a better understanding and design of these structural materials. With a nanoindenting atomic force microscope (NI-AFM), whi ch uses diamond tips, such measurements are possible on a nanometer sc ale. Measurements on the microstructure of superalloys are presented, where different precipitates with sizes in the range of 100 nm are cha racterized by their different hardness values. In addition, this new t echnique was used to characterize the nanohardness of the plastic zone and stress fields of cracks and grain boundaries. Therefore, crack ti ps of in-situ loaded bending specimens of intermetallic alloys (NiAl) were investigated. The measurements show a change in nanohardness and elasticity from the distance of interfaces.