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The trend of neutron-scattering studies of hard materials.

By C.-K. Loong

Abstract

Future high-tech applications will undoubtedly demand materials for carrying out complex tasks under stringent or adverse conditions. One of the important goals in materials design is to be able to introduce specific desirable properties in the components at an early stage during fabrication and to predict the performance of the final product. This approach requires a database of atomic-level structures and response of a variety of key materials and sophisticated algorithms for large-scale computations. Slow (cold to epithermal) neutrons probe the organization and dynamic response of atomic nuclei and electrons in a substance (bulk and low-dimensional) thereby providing a valuable means for a microscopic interpretation of materials properties. For decades neutron technologists and instrument scientists have striven to improve the neutron sources and instrumentation for condensed-matter research. In this International Workshop of the JHT Projects and the N-Arena, I wish to comment on the trend of instrument development, using some recent studies of hard materials as an example. The requirement for high strength at high temperatures has led to intense studies of nitride- and carbide-based ceramics. Additional incentives include the lower density, lower thermal expansion, and better corrosion and oxidation resistance of ceramics as compared to metals. However, the current strength and reliability of nitride and carbide ceramics are not sufficient to replace the metallic counterparts such as heat engine components. The knowledge of atomic short-to-long 1 range ordering, the microstructure of the crystalline grains and intergranular phases as well as the dynamic response of atoms to applied force and temperature fields is an important prerequisite for the realization of wide-spread high-temperature applications of ceramics. The goal of neutron-scattering methodology is to provide the best means for high-resolution characterization of these properties over a wide range of length and time scales (0.1-1000 nm and 10{sup {minus}8}-10{sup {minus}13} sec). Obviously, many different kinds of instruments have to be developed in parallel with the advancement of neutron sources

Topics: Cold Neutrons, Mechanical Properties, Epithermal Neutrons, Neutron Diffraction, Phase Studies, Heat Engines, 36 Materials Science, Thermal Expansion, Carbides, Nitrides, Oxidation, Microstructure, Corrosion Resistance, Ceramics
Publisher: Argonne National Laboratory
Year: 1998
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Provided by: UNT Digital Library
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