Grain boundary electronic structure and high-temperature plastic flow in polycrystalline Al2O3

Hidehiro Yoshida, Yuichi Ikuhara, Taketo Sakuma

    Research output: Contribution to journalConference article

    1 Citation (Scopus)

    Abstract

    High temperature creep deformation in fine-grained, polycrystalline A1 2O3 is suppressed by the doping of 0.1 mol% LuO 1.5 or ZrO2, while that is accelerated by MgO or TiO 2-doping at 1250°C. The difference in the creep resistance is considered to be originated from change in the grain boundary diffusivity in Al2O3 due to the grain boundary segregation of the dopant cation. Change in the chemical bonding state in the cations-doped Al 2O3 is examined by a first-principle molecular orbital calculations using DV-Xα method based on [Al5O 21]27- cluster model. The dopant effect on the high-temperature creep resistance in polycrystalline Al2O 3 is in good agreement with the change in the ionic bonding strength between Al and O. The change in the chemical bonding strength can be explained in terms of effects of both dopant cation and accompanying vacancy, which changes constitutions of molecular orbitals and the chemical bonding strength in Al2O3.

    Original languageEnglish
    Pages (from-to)263-266
    Number of pages4
    JournalKey Engineering Materials
    Volume247
    Publication statusPublished - 2003 Jan 1
    EventAdvanced Ceramics and Composites - Shanghai, China
    Duration: 2002 Nov 192002 Nov 22

    Keywords

    • Alumina
    • Creep
    • Grain Boundary
    • HRTEM
    • Molecular Orbital Calculation

    ASJC Scopus subject areas

    • Materials Science(all)
    • Mechanics of Materials
    • Mechanical Engineering

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