1 / 16

Measuring Strain Using X-Ray Diffraction

Measuring Strain Using X-Ray Diffraction. By: James Belasco. What is Strain?. When a force is applied materials deform in two ways It will deform and then revert to its original shape (reversible) Change its shape permanently (irreversible). The Structure of Materials.

forrest-herrera
Télécharger la présentation

Measuring Strain Using X-Ray Diffraction

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. Measuring Strain Using X-Ray Diffraction By: James Belasco

  2. What is Strain? • When a force is applied materials deform in two ways • It will deform and then revert to its original shape (reversible) • Change its shape permanently (irreversible)

  3. The Structure of Materials • At the local level, solids are composed o crystalline lattices • Atoms in these crystal structures are arranged in different crystal shapes depending on the material

  4. Lattice Under Stress • In reversible strain the bonds act like springs • Strain “stretches” the bonds in the lattice without breaking them

  5. Who’s More Flexible?

  6. How does a polycrystalline material distribute strain? ? 1 2 1 2 + = ? or

  7. Polycrystalline Materials • Nanocrystalline structures are made of a large number of randomly oriented crystals • How does the bulk property of the material relate to the individual crystallites?

  8. d0 d0 d2* Strained Sample d1* The Value of X-Ray Diffraction Normal Space Diffraction Space d0 d0 Strain d2* d1* Figure Compliments of Matt Bibee, SULI 2006

  9. Strain Equations x y z x a = y z

  10. The Apparatus Detector Sample Beam

  11. Straining Iron [110] [200] • Sets of crystals oriented in a particular direction from their own ring • Iron produces three rings [211]

  12. One Ring χ Transformation Q To Have Cake • Diffraction images are transformed to a different coordinate system or “caked” χ Q

  13. [211]: 207.3 Error: 9.2 [110]: 177.5 Error: 10.9 [200]: 152.3 Error: 6.05 Straining Iron • The slopes of the lines give us the elastic modulus in a crystallographic direction Strain Direction

  14. How far can you stretch? Single Crystal Values 110  210 GPa 200  125 GPa 211  210 GPa Measured Values 110  177 ± 11 GPa 200  152 ± 6 GPa 211  207 ± 9 GPa ~ ~ The polycrystalline sample exhibits properties of the single crystal

  15. So what Really Happens? 1 2 + = ?

  16. Acknowledgements • Department of Energy, SLAC, and SSRL • Apurva Mehta • David Bronfenbrenner

More Related