Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-24T15:44:31.939Z Has data issue: false hasContentIssue false
  • English
  • Français

The Precession Technique in Electron Diffraction and Its Application to Structure Determination of Nano-Size Precipitates in Alloys

Published online by Cambridge University Press:  22 January 2004

J. Gjønnes ,
V. Hansen  and
A. Kverneland
J. Gjønnes
Affiliation:
Center for Materials Science, University of Oslo, Gaustadalleen 21, N-0349 Oslo, Norway
V. Hansen
Affiliation:
Stavanger University College, Department of Technology and Natural Sciences, P.O. Box 2557, Ullandhaug, N-4091 Stavanger, Norway
A. Kverneland
Affiliation:
Stavanger University College, Department of Technology and Natural Sciences, P.O. Box 2557, Ullandhaug, N-4091 Stavanger, Norway
Get access

Abstract

Crystal structure of nano-scale precipitates in age-hardening aluminum alloys is a challenge to crystallography. The utility of selected area electron diffraction intensities from embedded precipitates is limited by double scattering via matrix reflections. This effect can be signally reduced by the precession technique, which we have used to collect extensive intensity data from the semicoherent, metastable η′-precipitate in the Al-Zn-Mg alloy system. A structure model in the space group P-62c is proposed from high-resolution microscopy and electron diffraction intensities. The advantages of using the precession technique for quantitative electron diffraction is discussed.

Keywords

electron diffractionprecession techniquealuminum alloyscrystal structure
Type
Research Article
Information
Microscopy and Microanalysis , Volume 10 , Issue 1 , February 2004 , pp. 16 - 20
Copyright
© 2004 Microscopy Society of America

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Andersen, S.J., Zandbergen, H.W., Jansen, J., Træholt, C., Tundal, U., & Reiso, O. (1998). The crystal structure of the β″ phase in Al-Mg-Si alloys. Acta Mater 46, 3283–3298.Google Scholar
Auld, J.H. & Cousland, S. Mck. (1974). Structure of the metastable η′-phase in aluminum-zinc-magnesium alloys. J Aust Inst Metals 19, 194–199.Google Scholar
Cowley, J.M. (1953). Structure analysis of single crystals by electron diffraction. (II) Disordered boric acid structure. Acta Crystallogr 6, 522–529.Google Scholar
Dorset, D.L. (1995). Structural Electron Crystallography. New York: Plenum.
Engdahl, T., Hansen, V., Warren, P.J., & Stiller, K. (2002). Investigation of fine-scale precipitates in Al-Zn-Mg alloys after various heat treatments. Mater Sci Eng 327, 59–64.Google Scholar
Gjønnes, J., Hansen, V., Berg, B.S., Runde, P., Cheng, Y.F., Gilmore, C.J., & Dorset, D.L. (1998a). Structure model for the phase AlmFe derived from three-dimensional electron diffraction intensity data collected by a precession technique. Comparison with convergent beam diffraction. Acta Crystallogr A 54, 306–319.Google Scholar
Gjønnes, K., Cheng, Y.F., Berg, B.S., & Hansen, V. (1998b). Corrections for multiple scattering in integrated intensities. Application to determination of structure factors in the [001] projection of AlmFe. Acta Crystallogr A 54, 102–119.Google Scholar
Li, X.Z., Gjønnes, J., Hansen, V., & Wallenberg, L.R. (1999). HREM study and structure modeling of the η′-phase, the hardening precipitate in commercial Al-Zn-Mg alloys. Acta Mater 47, 2651–2659.Google Scholar
Own, C.S., Subramanian, A.K., & Marks, L.D. (2004). Quantitative analyses of precession diffraction data for a large cell oxide. Microsc Microanal 10, in press.Google Scholar
Sinkler, W., Bengu, E., & Marks, L.D. (1998). Application of direct methods to dynamical electron diffraction data for solving bulk crystal structures. Acta Crystallogr A 54, 591–605.Google Scholar
Sørbrøden, E., Runde, P., & Olsen, A. (1998). Design of a guided-beam system for Jeol 2000FX used for precession experiments in TEM. Proceedings of ICEM 14 (Cancun, Mexico), vol. 1, pp. 425–426. Bristol, UK: Institute of Physics Publishing.
Taftø, J. & Metzger, T.H. (1985). Large-angle convergent-beam electron diffraction: A simple technique for the study of modulated structures with application to V2D. J Appl Crystallogr 18, 110–113.Google Scholar
Vincent, R. & Bird, D.M. (1986). Measurement of kinematic intensities from large-angle electron diffraction patterns. Philos Mag A 53, L35–L40.Google Scholar
Vincent, R. & Midgley, P.A. (1994). Double conical beam-rocking system for measurement of integrated electron diffraction intensities. Ultramicroscopy 53, 271–281.Google Scholar
Voigt-Martin, I.G., Yan, D.H., Yakimansky, A., Schollmeyer, D., Gilmore, C.J., & Bricogne, G. (1995). Structure determination by electron crystallography using both maximum-entropy and simulation approaches. Acta Crystallogr A 51, 849–868.Google Scholar
Weirich, T.E., Ramlau, R., Simon, A., Hovmöller, S., & Zou, X.D. (1996). A crystal structure determined to 0.02 Å accuracy by electron crystallography. Nature 382, 144–146.Google Scholar
Weirich, T.E., Winterer, M., Seifried, S., Hahn, H., & Fuess, H. (2000). Rietveld analysis of powder diffraction data from nano-crystalline anatase, TiO2. Ultramicroscopy 81, 263–270.Google Scholar
Zandbergen, H.W., Jansen, J., Cava, R.J., Krajewski, J.J., & Peck, W.F. (1994). Structure of the 13-K superconductor La3Ni2B2N3 and the related phase LaNiBN. Nature 372, 759–761.Google Scholar
Zvyagin, B.B. (2001). From electron diffraction by clays to modular structures. Crystallogr Rep 46, 550–555.Google Scholar