The Nature and Multiscale Techniques for Characterizatoin of Mechanical Properties: from Nanostructured Materials to Single Macromolecules Part III. Nanoindentation and Atomic Mechanisms of Local Plastic Deformation

Abstract

Up-to-date techniques for characterization of mechanical properties of materials (including biological ones) at all scale levels: macro-, micro-, nano- and atomic-molecular ones are considered. Particular attention is paid to atomic mechanisms of transition from elastic to plastic deformation. It is shown that a decrease in the size of crystalline object or its structural elements leads to a decrease in the activation volume, which characterizes the sizes of plastic deformation carrier, up to a volume comparable with atomic/ionic volume. It means that carriers of plastic deformation in nanoobjects are predominantly individual atoms and/or their small-atomic-clusters. As the size of the object or the size of plastic deformation zone increase, dislocation mechanisms start to operate. In macrobodies the formation of large clusters of dislocations, twins, grain boundaries migration, pore formation, micro-cracks become dominant.