1 / 18

Residual Stress Characterization In Zirconium Oxides Using Synchrotron XRD

Residual Stress Characterization In Zirconium Oxides Using Synchrotron XRD. Efthymios Polatidis, Philipp Frankel, Jianfei Wei, Michael Preuss. Manchester Materials Science Centre, The University of Manchester, Grosvenor Street , Manchester M1 7HS, United Kingdom. Uses and corrosion of Zr-Alloys.

nita
Download Presentation

Residual Stress Characterization In Zirconium Oxides Using Synchrotron XRD

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Residual Stress Characterization In Zirconium Oxides Using Synchrotron XRD Efthymios Polatidis, Philipp Frankel, Jianfei Wei, Michael Preuss Manchester Materials Science Centre, The University of Manchester, Grosvenor Street , Manchester M1 7HS, United Kingdom

  2. Uses and corrosion of Zr-Alloys Zr-alloys used as cladding materials of the fuel rods. In service environments oxidation occurs limiting their service life. OXIDE METAL

  3. Uses and corrosion of Zr-Alloys Zr-alloys used as cladding materials of the fuel rods. In service environments oxidation occurs limiting their service life. Better understanding of the corrosion mechanisms could lead to improvement of the burn up efficiency. Residual stresses in the oxide are believed to play key role on the corrosion properties of the material.

  4. Stresses in Zr-alloys oxides • Origin of stresses Transformation strain. Transformation of Zr-ZrO2 is accompanied by volume dilatation. (volume of ZrO2 is 1.56 times greater than Zr) • How do stresses affect oxidation? • The tetragonal phase can be stress stabilised • As oxidation proceeds stresses might be reduced in the oxide away from the interface, which could lead to t m phase transformation • This phase transformation is associated with a further volume increase ─ cracks─ acceleration of corrosion kinetics

  5. Synchrotron X-Ray diffraction experiment at BESSY EDDI, Berlin Fixed angle detector psi θ Incoming white beam Diffracted beam Sample Residual strain (along the oxide thickness) can be extracted by altering the incident angle theta. Sin2psi method.

  6. Synchrotron X-Ray diffraction experiment at BESSY EDDI, Berlin Diffraction spectrum for each measurement angle ψ Increasing penetration Zr(103) Zr(002) Zr(102) m(-111) m(002) Zr(101) m(211) m(221) Zr(100) m(-211) m(-122) t(101) • Higher energy - greater penetration - depth profile

  7. Penetration depth with 2θ θ θ θ Lowest angle= highest energy Max. Pen. greater than oxide thickness Highest angle= lowest energy Max. Pen. Only samples part of oxide thickness ≈ oxide oxide oxide metal metal metal

  8. Results ZIRLO™ SR/80 days at 360°C ZIRLO™ SR/160 days at 360°C Oxide Metal Oxide Metal Residual Stress (MPa) Residual Stress (MPa) Distance from outer surface (um) Distance from outer surface (um) Maximum stress - close to the O/M interface

  9. Synchrotron XRD experiment at ESRF ID11, France Using XRD diffraction in transmission geometry and monochromatic beam, the setup allows strain characterization along the oxide thickness: Diffracted cones Incoming beam Residual strain (along the oxide thickness) can be extracted by comparing “strain free” samples with strained lattice spacing values. (dstrained-dstrain free)/dstrained= strain Detector Sample

  10. Synchrotron XRD experiment at ESRF ID11, France Diffraction Pattern 95º 85º oxide 5º y -5º z For each measurement point

  11. Synchrotron XRD experiment at ESRF ID11, France Diffraction pattern Diffraction spectrum 95º 85º 5º -5º For each measurement point

  12. Stress calculation • Strain= (dhkl-d0)/d0 • Extract stress tensor using Hooke’s Law, knowing in plane (εxx) and out of plane (εyy) strain. y z oxide x FE analysis suggests that the out of plane stress (σyy) is equal to zero, thus out of plane strain (εyy) occurs due to Poisson’s contraction. Metal

  13. Results

  14. Creep of the substrate Compressive stresses - Oxide Balancing tensile stresses-Metal- High temperature/time-Creep FEM simulating the stress due to oxide volume expansion and relaxation due to creep Relaxed compression Relaxed compression Relaxed compression Tension High T compression Relaxed Tension High T Relaxed Tension High T High T Tension High T compression compression

  15. Creep of the substrate Evolution of strain versus oxide thickness Measured Elongation by creep (M. Blat‐Yrieix et. al) FEM creep strain Blat-Yrieix M. et. al, Toward a Better Understanding of Dimensional Changes in Zircaloy-4: What is the Impact Induced by Hydrides and Oxide Layer?, Journal of ASTM International, Vol. 5, No. 9, 2008.

  16. Creep of the substrate Distance from O/M interface (μm) Residual Stress (Mpa)

  17. Conclusions • A stress profile exists through oxide thickness - maximum compressive stresses near the O/M interface stress decay away from interface may enable tetragonal to monoclinic phase transformation. • Stress reduces with oxidation time. • A stress profile may be produced by creep of substrate – however • the shape of the measured profile does not match the profiles predicted by substrate creep alone. • Stress profile affected by other factors such as cracks between the oxide layers.

  18. Thank you!

More Related