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Microstructure and Indentation Fracture of Dysprosium Niobate

Published online by Cambridge University Press:  01 June 2005

Byong-Taek Lee
Affiliation:
Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
Waltraud M. Kriven*
Affiliation:
Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

The high-temperature indentation fracture and microstructures of dysprosium niobate (DyNbO4) were investigated by optical, scanning, and transmission electron microscopy (OM, SEM, and TEM). Polycrystalline samples were sintered at 1350 °C for 3 h and cut into 3 mm disks for TEM. The disks were indented in a Nikon QM (Tokyo, Japan) hot hardness indenter at room temperature up to 1000 °C. Many lamellar twins having different widths were observed by TEM as well as intergranular microcracks. The room temperature hardness was relatively low at 5.64 GPa and decreased with elevated temperatures. Crack lengths were short, showing a typical micro-cracking effect. In the sample indented at 1000 °C, dislocations in periodic arrays were evident, and their density increased markedly due to heavy plastic deformation.

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Articles
Copyright
Copyright © Materials Research Society 2005

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