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   <title>Fine-grained Refractory Materials Group, NIMS</title>

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<P align="right">UP DATE July 27, 2009</P>

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<P align="right"><FONT color="#ff0000"><A href="index.html">Japanese</A></FONT></P>

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<font COLOR="#023095">Fine-Grained Refractory Materials Group</font></h2>

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<a href="summary_e.html"><align=middle alt="Outline of Current Research" border="0" hspace="0"><b>Outline of Current Research</b></a><br><br>

<a href="members_e.html"><align=middle alt="People" border="0" hspace="0"><b>People</b></a><br><br>

<a href="publications_e.html"><align=middle alt="Group Publication" border="0" hspace="0"><b>Group Publication</b></a><br><br>

<a href="recruitment_e.html"><align=middle alt="Posdocs" border="0" hspace="0"><b>Posdocs</b></a><br><br>

<a href="index.html"><align=middle alt="Japanese" border="0" hspace="0"><b>Japanese</b></a><br><br>

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<h2 align=left><font COLOR="#023095">Overview</font></h2>


Our research addresses functional structural materials synthesized from 

Al<sub>2</sub>O<sub>3</sub>, ZrO<sub>2</sub>, Y<sub>2</sub>O<sub>3</sub>, MgO and other oxides. 

Special attention is placed on the combination between excellent mechanical strengths and 

some selected isotropic or anisotropic properties such as superplasticity, transparency and 

electrical conductivity.　

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In studies on superplasticity, we have attained high-strain-rate superplasticity (HSRS, Fig. 1(a)) 

at a strain rate of 1 s<sup>-1</sup> (<i>Nature</i> <b>413</b> (2001) 288-291), 

a large tensile ductility of 2500% at 0.09 s<sup>-1</sup> (Fig. 1(c)) and HSRS 

at a relatively low temperature around 1350<sup>o</sup>C 

in monolithic and composite (Fig. 1(b)) materials. In basic research, 

we have obtained new information on the relationship between superplasticity and 

the following factors: nanometer-sized inter- and intra-granular structures, segregation 

along grain-boundaries and dynamic processes such as grain growth, grain-boundary sliding 

and intergranular cavitation. 

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We have started new projects for developing new functional materials. For this purpose 

we have been concentrating on the relationship between grain-boundary chemistry and 

transport phenomena, synthesis of nano-structured composites, synthesis of transparent polycrystals 

and analysis of flow behavior in a textured material. 


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Fig. 1 R & D of high-strain-rate superplastic oxide ceramics: (a) the relationship between the strain rate and  

tensile ductility, (b) transmission electron micrograph of ZrO<sub>2</sub>-30%MgAl<sub>2</sub>O<sub>4</sub> that exhibits HSRS and  

(c) a large tensile ductility of 2500% attained in Al<sub>2</sub>O<sub>3</sub>-ZrO<sub>2</sub>-MgO/nAl<sub>2</sub>O<sub>3</sub>. 

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<h2 align=left><font COLOR="#023095">Current research</font></h2>


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<li>Development of high-strain-rate superplastic oxide ceramics</li>

<li>Theoretical analysis and simulation of high-temperature deformation and relating phenomena in polycrystalline solids</li>

<li>Analysis of superplastic deformation behavior in fine-grained oxide ceramics</li>

<li>Analysis of intergranular cavitation and cracking in superplastic ceramics</li>

<li>Synthesis of nano-structured oxide composites</li>

<li>Analysis of the relationship between grain boundary chemistry and transport phenomena</li>

<li>Synthesis of transparent oxides by spark plasma sintering</li>

<li>Analysis of high-temperature flow behavior in textured &alpha;-alumina ceramics</li>

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Address: 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan.<br>

Telefax: +81-29-859-2501<br>

E-mail: <img src="Hiraga-mail.jpg" height="13"><br>

Go To <a href="http://www.nims.go.jp/eng/index.html">National Institute for Materials Science (NIMS)</a><br>

Go To <a href="http://www.nims.go.jp/ncc/">Nano Ceramics Center, NIMS</a><br>

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