Nanocrystalline materials exhibit the outstanding properties and represent a new class of structural materials having a wide range of applications. In particular, there is considerable interest in developing nanocrystalline materials to be used as functional materials in aerospace applications, automotive industry, wear applications, MEMS, etc. The future progress in these high technological applications of nanocrystalline materials crucially depends on development of new methods of their fabrication and understanding of the underlying nano-scale and interface effects causing their unique mechanical properties.