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Grain boundary dislocation interactions in nanocrystalline Al2O3

Published online by Cambridge University Press:  03 March 2011

Sampa Dhabal
Sampa Dhabal*
Affiliation:
Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur – 721302, India
*
a) Address all correspondence to this author. e-mail: sampa@phy.iitkgp.ernet.in
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Abstract

To explore the mechanism of grain growth, gas phase synthesized nanopowders of Al2O3 were heated in ambient conditions at elevated temperatures. Transmission electron microscopy and x-ray line broadening studies were performed to determine the microstructural parameters like crystallite size and root-mean-square (rms) strain. Increase in crystallite size with a decrease in dislocation density was observed for annealing the powder at higher temperatures. From a detailed analysis of the dislocation interactions, it was shown that polygonization like interaction of dislocations is the primary cause for such growth. A model for such growth is proposed. From the measured values of the rms strain and crystallite size at different temperatures, the ratio of the bulk to the shear modulus was determined. The measured ratio was found, within experimental uncertainties, to be close to the bulk value.

Keywords

DislocationsTransmission electron microscopy (TEM)X-ray diffraction (XRD)
Type
Articles
Information
Journal of Materials Research , Volume 22 , Issue 4 , April 2007 , pp. 900 - 907
Copyright
Copyright © Materials Research Society 2007

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