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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.45  No.7 (2004)  >  pp.2078-2082

MATERIALS TRANSACTIONS
<<Previous article Vol.45  No.7 (2004)   pp.2078 - 2082 Next article>>

Improvement of High-temperature Creep Resistance in Polycrystalline Al2O3 by Cations Co-doping

Shuichi Yasuda1), Hidehiro Yoshida1), Takahisa Yamamoto1) and Taketo Sakuma1)
1) Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo

High-temperature creep resistance in cations co-doped polycrystalline Al2O3 was examined by uniaxial compression creep test at 1250°C. The dopant oxides used in this study were 0.1 mol% of YO1.5, ZrO2, SrO, MgO and TiO2. The creep rate in Al2O3 was significantly changed by cations co-doping. For instance, Zr/Y co-doping suppressed the creep rate in Al2O3 by a factor of about 400. A high-resolution transmission electron microscopy (HREM) and nano-probe energy dispersive X-ray spectroscopy (EDS) analysis revealed that Y and Zr cations segregate along grain boundaries. The grain boundary diffusion in Al2O3 was supposed to be retarded by the segregation of Y and Zr cations. A first-principle molecular orbital calculation was made for cations co-doped Al2O3 and cation singly doped Al2O3 model cluster. The creep rate was correlated with the value of net charge in oxygen anion. The net charge of oxygen anion was one of the most important factors to determine the creep resistance in Al2O3.


Keyword:
co-doped alumina, creep, ionicity, grain boundary, molecular orbital calculation

Received: January 30, 2004
Accepted: April 06, 2004 , Published online: June 24, 2005
Copyright (c) 2005 The Japan Institute of Metals

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