High-temperature deformation and fracture behavior of Al2O3-Y2O3 doped silicon nitride

Yuichi Ikuhara, Hiroshi Suzuki, Toshiyuki Suzuki

    Research output: Contribution to journalArticlepeer-review

    2 Citations (Scopus)

    Abstract

    In order to clarify the high-temperature deformation and fracture behavior of Al2O3-Y2O3 doped Si3N4, four-point bending tests were conducted at temperatures from room temperature to 1790K and at strain rates from l.Sx 10-6s-1 to 3x10-2s-1 in a nitrigen gas of 1.013x105 Pa (1 aim). As a result, the mechanical equation of state at yield stress was obtained as ε=A(σy/E)mexp(-Q/RT), where m =3.9 in the low temperature range or high strain-rale range, where m =1.7 in the high temperature range or low strain-rate range. The critical strain rate at which m changed shifted to high strain-rate side as temperature rises. It was suggested that plastic deformation of the Si3N4 was controlled by grain boundary sliding with cavity formation in the range of m=1.7, and dislocation motion and micro-crack propagation in the range of m=3.9. The activation energy for deformation Q was almost independent of strain rate when m=3.9, while Q tended to increase with decreasing strain rate when m=1.7. The relationship between deformation and fracture in Si3N4 was discussed on the basis of m value and fracture mode.

    Original languageEnglish
    Pages (from-to)430-434
    Number of pages5
    JournalMaterials Transactions, JIM
    Volume37
    Issue number3
    DOIs
    Publication statusPublished - 1996

    Keywords

    • Cavitation, high-temperature deformation, activation energy for deformation
    • Dislocation
    • Grain boundary sliding
    • Micro-crack
    • Silicon nitride
    • Strain rale
    • Stress exponent

    ASJC Scopus subject areas

    • Engineering(all)

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