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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.45  No.7 (2004)  >  pp.2073-2077

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Effect of MgAl2O4 Spinel Dispersion on High-Strain-Rate Superplasticity in Tetragonal ZrO2 Polycrystal

Koji Morita1), Keijiro Hiraga1), Byung-Nam Kim1) and Yoshio Sakka1)
1) National Institute for Materials Science

The effect of second phase dispersion on high-strain-rate superplasticity was examined in tetragonal ZrO2 dispersed with 30 vol% MgAl2O4 spinel. The spinel particle enhances the diffusivity of ZrO2 by supplying small amounts of aluminum and magnesium into ZrO2 and suppresses grain growth by grain boundary pinning. After superplastic flow, the spinel particles highly elongate along the tensile direction. In the spinel particles, intragranular dislocations were observed, indicating that the spinel particles may contribute to the relaxation of stress concentrations around grain junctions exerted by grain boundary sliding. Comparison with earlier studies suggests that the dispersion of spinel particles can attain high-strain-rate superplasticity in tetragonal ZrO2 through providing the following positive factors simultaneously; (i) the suppressed grain growth, enhanced accommodation process due to the accelerated (ii) diffusivity and (iii) stress relaxation.

tetragonal zirconia polycrystal, high-strain-rate superplasticity, accommodation process, intragranular dislocation

Received: January 29, 2004
Accepted: March 15, 2004 , Published online: June 24, 2005
Copyright (c) 2005 The Japan Institute of Metals



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