NANOSTRUCTURED MATERIALS

In the cores of lattice defects (e.g. dislocations, grain boundaries, phase boundaries etc.) a special state of solid matter exists due to the forces (constraints) between the atoms (molecules) in the core region of the defects and the atoms (molecules) in the surrounding strained crystal lattices. These constraints result in the formation of a solid state structure characterized by a low density (typically 60 - 80 % of the crystal density) and a very broad distribution of nearest neighbour spacings. It is the basic idea of Nanostructured Materials to utilize the atomic structures formed in the cores of defects to generate a new class of materials. This goal is achieved by incorporating so many defects into a (formerly perfect) crystal that about 50 vol % of the material consists of defect cores. The results of studies by means of electron microscopy, neutron and x-ray diffraction, various types of spectroscopy and property measurements agree with these ideas. Nanostructured Materials exhibit properties that deviate (sometimes by many orders of magnitude) from the properties of crystals and glasses with the same chemical composition.