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Novel Nanostructured Metal and Ceramic Composites

Published online by Cambridge University Press:  11 February 2011

J. Narayan*
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695–7916.
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Abstract

We have designed a unique synthesis procedure to create nonomaterials of uniform grain size and control the chemistry of interfaces between the grains. The metastability of nanocrystalline materials is a major challenge which can be addressed by controlling the chemistry of interfaces. The hardness of these films having a uniform size was measured as a function of grain size using a nanoindentation technique. It was found that hardness increased with decreasing grain size in accordance with Hall-Petch model. However, below a critical grain size we observed a decrease or softening with a further decrease in grain size. These observations in metals and ceramics are modeled in view of intragrain deformation (Hall-Petch regime) and intergrain deformation (grain boundary shear/sliding )in the softening regime. Since we can change the alloying of interfacial region, we can address the metastability as a function of temperature, which is crucial from applications viewpoint of these materials.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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