The processing and mechanical behaviour of bulk nanostructured materials are one of the most interesting new fields of research on advanced materials systems. Many nanocrystalline materials possess very high strength with still good ductility, and exhibit high values of fatigue resistance and fracture toughness. There has been continuing interest in these nanomaterials for use in structural and biomedical applications, and this has led to a large number of research programs worldwide. This book focuses on the processing techniques, microstructures, mechanical and physical properties, and applications of bulk nanostructured materials, as well as related fundamental issues. Only since recently can such bulk nanostructured materials be produced in large bulk dimensions, which opens the door to their commercial applications.