This book concentrates on both understanding and development of nanocrystalline materials. The original relation that connects grain size and strength, known as the Hall-Petch relation, is studied in the nanometer grain size region. The breakdown of such a relation is a challenge. Why and how to overcome it? Is the dislocation mechanism still operating when the grain size is very small, approaching the amorphous limit? How do we go from the microstructure information to the continuum description of the mechanical properties?

* Covers all aspects of physical metallurgy and behavior of metals and alloys. * Presents the principles on which metallurgy is based. * Concepts such as heat affected zone and structure-property relationships are covered. * Principles of casting are clearly outlined in the chapter on solidification. * Advanced treatment on physical metallurgy provides specialized information on metals.

These proceedings of the "Second International Conference on Nanomaterials by Severe Plastic Deformation" review the enormous scientific avalanche that has been developing in the field over recent years. A valuable resource for any scientist and engineer working in this emerging field of nanotechnology.

In the fall of 1998, Prof. Sergey Firstov invited me to the Frantcevych Institute for Problems of Materials Science (IPMS) in Kyiv, Ukraine to discuss possible collaborations in the area of advanced metals research. During this visit, a strong mutual interest was evident in a broad range of structural metals technologies, and a quick friendship was established. Countless subsequent emails and a reciprocal visit to the U. S Air Force Research Laboratory by Prof. Firstov and a team of scientists from IPMS ensued to discuss and detail a broad collaboration in the area of structural metals. Two years after the initial visit, a major investment by the U. S. Air Force Office of Scientific Research (AFOSR) was established to pursue the technologies defined by these interactions. The annual reviews of the AFOSR Ukrainian Metals Initiative were held in late May, a most beautiful time in Kyiv when the lilacs are in bright display and the air is scented with the smell of falling blossoms from the chestnut trees that line the major streets and many parks. The sunny days and mild evenings provide a welcome break from winter, and on weekend evenings festive crowds spill onto the Khreshchatyk, Kyiv’s downtown boulevard, to listen to street musicians, watch jugglers and comedians, or simply to celebrate with friends. The annual reviews featured long days of intensive discussion of technical progress, followed in the evenings by the warm hospitality of the Ukrainian hosts.

This book focuses on the emerging class of new materials characterized by ultra-fine microstrucures. The NATO ASI which produced this book was the first international scientific meeting devoted to a discussion of the mechanical properties and deformation behavior of materials having grain sizes down to a few nanometers. Topics covered include superplasticity, tribology, and the supermodulus effect. Review chapters cover a variety of other themes including synthesis, characterization, thermodynamic stability, and general physical properties. Much of the work is concerned with the issue of how far conventional techniques and concepts can be extended toward atomic scale probing. Another key issue concerns the structure of nanocrystalline materials, in particular, what is the structure and composition of the internal boundaries. These ultra-fine microstructures have proved to challenge even the finest probes that the materials science community has today.