........ published in NEWSLETTER # 49
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........ published in NEWSLETTER # 49
MECHANICAL PROPERTIES AND DEFORMATION BEHAVIOR OF MATERIALS HAVING ULTRA_ FINE MICROSTRUCTURES
by Dr. M.A. Nastasi, Los Alamos National Laboratory, Los Alamos (U.S.A.)
This NATO Advanced Study Institute was held in order to assess our current state of knowledge in the field of mechanical properties and deformation behavior in materials with ultra_fine microstructure, to identify opportunities and needs for further research, and to identify the poten for technological applications.
In an attempt to meet the demand for new ultra_high strength materials, the processing of novel material configurations with unique microstructure is being explored in systems which are further and further from equilibrium. One such class of emerging materials is the so_called nanophased or nanostructured materials. This class of materials includes metals and alloys, ceramics, and polymers characterized by controlled ultra_fine microstructural features in the form of layered, fibrous, or phase and grain distribution. While it is clear that these materials are in an early stage of development, there is now a sufficient body of literature to fuel discussion of how the mechanical properties and deformation behavior can be controlled through control of the microstructure.
The focus of the Institute and the resulting publication (NATO ASI SERIES E233) was on the emerging class of new materials characterized by ultra_ fine microstructures. The Institute was the first international scientific meeting devoted to a discussion on the mechanical properties and deformation behavior of materials having grain sizes down to a few nanometers. Included in these discussions were the topics of superplasticity, tribology, and the supermodulus effect. Lectures were also presented which covered a variety of other themes including synthesis, characterization, thermodynamic stability, and general physical properties. Many of the discussions concerned 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 the structure and composition of the internal boundaries. These ultra_fine microstructures have proved to challenge even the finest probes that the material sciences community has today.
On this occasion it should be emphasized that the NATO Science Committee has a strong Special Programme in `Nanoscale Science and Technology' under which a considerable number of scientific meetings are being organized. The majority of the resulting book publications will appear in the E_Series of the NATO ASI SERIES published by KLUWER Academic Publishers, Dordrecht (The Netherlands).
Reference books: B189, B206, E121, E233, E260