  NPs are ultrafine-grain crystal or amorphous substances which are as small as
100nm. They have unique physical, chemical and mechanical properties, which are
very different from those of large scale materials. This uniqueness is
attributed to the fact that the number of atoms in the surface layer and in the
bulk is commensurable. As the atoms in the surface layer of nanoparticles have
their counterparts from one side only, their balance is impaired, and the
resulting structure relaxation leads to the displacement of atomic spacing in a
2-3nm layer. Therefore the surface layers expand while internal layers
compressed, as these are exposed to an excessive Laplace pressure of up to
hundreds kilobars. Nanoparticles have a highly distorted lattice that has an
effect on activation energy of most of the processes they are involved in, by
changing their nature and sequence. Nanoscale implies absolutely new effects,
properties and processes which are defined by the laws of quantum mechanics,
size quantization in small-scale structures, surface-bulk ratio, and other
factors. Due to exceptionally small sizes and good reactivity of NP particles,
it looks promising to use them in metal melts as crystallization centers to
enable structure refinement of cast products. As well known, the grains are
finer, the better are mechanical properties of cast products produced from
these alloys. After considering a number of options, an efficient method of
nanopowder introduction into a liquid metal was proposed. This method avoids
all of the above problems and consists in pressing of 5-9.5mm diameter rods or
wires that contain aluminum particles (granules and nanopowder). Nanopowder
contents in rods added NP to alloys being no more than 0.05%, and sometimes
even thousandths of one percent.
