STP633

    High Temperature Strain Behavior of Zircaloy-4 and Zr-2.5Nb Fuel Sheaths

    Published: Jan 1977


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    Abstract

    The ballooning behavior of Zircaloy-4 fuel sheaths at high temperatures has been reported previously by Hardy. Similar tests have been done on Zr-2.5Nb tubes. In both materials, the importance of the phase transformation from hexagonal close-packed to body-centered-cubic structure is evident. Towards the upper boundary of the two-phase (α + β) region where β-phase material would dominate, there is a marked discontinuity in the strain versus temperature results. They indicate that the solid solution strengthening in the β-phase is more effective than the second phase particle strengthening in the α-phase.

    At normal operating temperatures, Zr-2.5Nb is stronger than Zircaloy-4. However, above 600°C it enters the two-phase temperature region and becomes weaker than Zircaloy-4 which is still within the α-phase. In the β-phase, where Zr-2.5Nb contains about twice as many atoms in solid solution as Zircaloy-4, the former again becomes stronger. At 1000°C, the strain rate of Zr-2.5Nb is about two orders of magnitude less than that of Zircaloy-4 at the same stress.

    Keywords:

    zirconium, zirconium alloys, mechanical properties


    Author Information:

    Hunt, CEL
    Fuel development engineer and research technologist, Atomic Energy of Canada Limited, Fuel Engineering Branch, Chalk River Nuclear Laboratories, Chalk River, Ontario,

    Foote, DE
    Fuel development engineer and research technologist, Atomic Energy of Canada Limited, Fuel Engineering Branch, Chalk River Nuclear Laboratories, Chalk River, Ontario,


    Paper ID: STP35564S

    Committee/Subcommittee: B10.02

    DOI: 10.1520/STP35564S


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