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 

5. Comparison 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 NECSA-WITS Workshop

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

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

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

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.  = 0º  = 10º  = 20º  = 30º  = 40º  = 50º  = 60º  = 70º  = 80º  = 89.7º Q 211 C Scattering plane compressive stress

18. Interaction HEI

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

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

21. Thermal sprayed Coating Ms H. Mathabatha, TUT

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

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

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

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

27. THANK YOU