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Near-surface diffraction capabilities at NECSA

Near-surface diffraction capabilities at NECSA. TP Ntsoane Diffraction Section 11 September 2015. OUTLINE. Introduction D8 Advance Sample stage & holder types D8 Discover Examples: Interaction with HEI Possible areas of collaboration Conclude. Introduction.

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Near-surface diffraction capabilities at NECSA

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  1. Near-surface diffraction capabilities at NECSA TP Ntsoane Diffraction Section 11 September 2015

  2. OUTLINE • Introduction • D8 Advance • Sample stage & holder types • D8 Discover • Examples: Interaction with HEI • Possible areas of collaboration • Conclude

  3. Introduction • Diffraction techniques are widely used in non-destructive materials characterisation. • Applications ranges from Phase Identification, Crystallite size determination, lattice parameter determination, crystallinity , strain/stress and texture. • Shallow penetration depth allows Near-surface region information • Two Bruker AXS diffractometers (formerly Siemens X-ray division) • D8 Advance • D8 Discover

  4. D8 Advance  D500 D8 Advance

  5. D500 NaI scintillation -2 goniometer D8 Advance Lynx eye detector (0 & 1 D mode) Sample stages - Goniometer Sample rotation Goebel mirror Online status Windows based Variable measurement time Comparison NECSA-WITS Workshop

  6. Sample stages • Automatic sample changer • Capillary stage • XYZ stage • Small angle X-ray scattering

  7. Rotated by 90° Transmission geometry Automatic changer Reflection geometry 9 sample holders (x7) Allows overnight measurement Sample types: powder, liquid, thin films Allows sample rotation during meas.

  8. Automatic changer con’t Δ2max = 0.003° Ok for most applications Superposed peaks from different multisample slots indicating variation in peak position

  9. XYZ stage • Useful for localized investigation • Localized characterization • Allows large samples Top view of XYZ stage

  10. Capillary stage • Useful for small amount of sample • Minimization of preferred orientation Challenges: filling the capillary with powder

  11. Sample holders • Standard • Reflection • = 25 mm, 40mm • = 25 mm Si crystal Domed-shape holder • Transmission • = 25 mm Capillary stage • = 50 m, 1mm, 2mm, 2.5mm wall thickness = 10m

  12. Superposed powder diffraction pattern of Cr2O3 on standard sample holder and dome-shaped and empty dome shaped sample holder. NECSA-WITS Workshop

  13. Possible investigations ● Grazing angle investigations: inc< 1 Thin films  Near-surface modifications ● Analysis of radioactive & environmentally sensitive samples

  14. D8 Discover • 2D detector Vantec500 • Laser & Video align • Eulerian cradle • 0.8mm collimator

  15. Applications Residual strain and stress investigation Texture analysis Micro Powder diffraction (Phase identification)

  16. Basic principle

  17. compressive stress Y = 0º Y = 10º Y = 20º Y = 30º Y = 40º Y = 50º Y = 60º Y = 70º Y = 80º Y = 89.7º Q211 Scattering plane C

  18. Interaction HEI

  19. Interaction with HEI Thin films Ms P. Mudau, Univ. of Johannesburg

  20. Grit-blasted Ti alloy cylinder Dr. N. Janse van Rensburg, Univ. of Johannesburg

  21. Thermal sprayed Coating Ms H. Mathabatha, TUT

  22. Micro Diffraction Phase identification in Friction Spot Stir Weld Mr P. Mubiayi, UJ

  23. Influence of fatigue on residual stress Mr M. Vhareta, WITS

  24. Texture analysis Pole figures of rolled Aluminium Software: Multex Prof R. Knutsen, Univ. of Cape Town

  25. Possible areas of collaboration • Near-surface characterization of • layered structures • modified surfaces i.e. grit-blasting, polishing etc •  Irradiated surfaces •  Engineering components • Thin film investigation • Micro-diffraction for localized investigation

  26. For more information: Tshepo Ntsoane tshepo.ntsoane@necsa.co.za Zeldah Sentsho zeldah.sentsho@necsa.co.za Andrew Venter andrew.venter@necsa.co.za African Light Source Conference and Workshop European Synchrotron Radiation Facility, Grenoble France 16th – 20th November 2015 http://www.saip.org.za/AfLS2015/.

  27. THANK YOU

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