1 / 20

Determination of Planar Defects together with Dislocations and Size-Distribution

Determination of Planar Defects together with Dislocations and Size-Distribution from Broadened X-ray Line Profiles Tam á s Ung á r Diffraction Laboratory, Department of Matrials Physics E ö tv ö s University Budapest, Hungary XX CONFERENCE ON APPLIED CRYSTALLOGRAPHY

fuller-knight
Download Presentation

Determination of Planar Defects together with Dislocations and Size-Distribution

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. Determination of Planar Defects together with Dislocations and Size-Distribution from Broadened X-ray Line Profiles Tamás Ungár Diffraction Laboratory, Department of Matrials Physics Eötvös University Budapest, Hungary XX CONFERENCE ON APPLIED CRYSTALLOGRAPHY 11-14 September 2006, Wisła, Poland

  2. Planar Defects (i) Intrinsic Stacking Faults (ii) Extrinsic Stacking Faults (iii) Twins

  3. Planar defects Stacking Faults in Ultrafine Nickel Ping Liu, Yuming Wang . Materials and Design21(2000) 155-57 100 nm

  4. FacetingandStacking Faultsparallelto theclose-packedplanes 100 nm

  5. 111 Planar fault (PF) Streaking to PF plane T Electron Diffraction on Magnesium-Fluoro-Germanate (courtesy of P. Kunzmann) hcp modulated stucture in a Westinghouse phosphor 111

  6. C A B C B C A A A B B B C C C C B B B B A A A A fcc sequence Intrinsic SF Twins Extrinsic SF

  7. Shift Calculated diffraction spectrum of 4% Extrinsic SF DIFFaX: Treacy MMJ, Newsam JM, Deem MW, Proc. Roy. Soc. London A, (1991) 433, 499-520.

  8. Calculated diffraction spectrum of 4% Extrinsic SF DIFFaX: Treacy MMJ, Newsam JM, Deem MW, Proc. Roy. Soc. London A, (1991) 433, 499-520. Asymmetry Shift

  9. Subreflections according to different hklpermutations

  10. Not “Strain” Broadening (111 is mirrored over K zero)

  11. Stacking Fault Profile : ISF =fd + f1L1 + f2L2 + f3L3  : Delta function Li : Lorentzian sub-profiles given by: breadths + shiftsvs.or fi : fractions of sub-profiles

  12. 5th order polinomials Subreflections of the {533} reflection (intrinsic SF) Shifts Breadths Data files for the Lorentzian Profile Functions: (1) shifts and breadths 5th order polinomials (2) Fractions of sub-reflections

  13. ~15.000 subreflections are reduced to 3 sets of data files for intrinsic extrinsic twin Fitting parameter:  (or )

  14. Input data for the fitting procedure: - coefficients of the the 5th order polinomials for each hkl subreflection family - fractions of the hkl subreflection families - profile functions for planar faults: Lorentzian functions

  15. Measured pattern Physically modeled Experimentally determined L. Balogh, G. Ribarik, T. Ungár, J. Applied Physics, 100, 023512 (2006) Philosophy of evaluation IMeas < = > IStrain * ISize* ISF * IInstr + BG Non-linear, least squares fitting IStrain : , M, q M = Re1/2 ISize : m,  ISF :  In cubic crystals altogether: 6 parameters

  16. Inert-Gas condensed copper T.Ungár, S.Ott, P.G.Sanders, A.Borbély, J.R.Weertman, Acta Materialia, 10, 3693-3699 (1998) Recent evaluation: L.Balogh,G.Ribarik, T.Ungár, J.Appl.Phys.100,023512(2006)

  17. Twins and grain size ininert-gas condensed Cu R.Mitra, T.Ungár, J.R.Weertman

  18. A Comparison of Grain Size Measurements by X-Ray Diffraction and Transmission Electron Microscopy R.Mitra, T.Ungár, J.R.Weertman TEM and X-ray grain size

  19. Twinning in Cu: below ~ 40 nm Twin densityvs. crystallite size: deformed Cu L.Balogh,G.Ribarik, T.Ungár, J.Appl.Phys.100,023512 (2006)

  20. Deformation twinning in nanocrystalline copper at room temperature and low strain rate X.Z.Liao, Y.H.Zhao, S.G.Srinivasan, Y.T.Zhu, R. Z. Valiev and D. V. Gunderov APPLIED PHYSICS LETTERS, 84 (2004) 592 A typical image of a fivefold twin. The twin boundaries are indicated by black arrows, and each twin domain is marked with 1 to 5, respectively. The twin center is highlighted with a black dot.

More Related