COMBINATION OF X - RAY AND ELECTRON DIFFRACTION FOR DETAILED ANALYSIS OF DEFORMATION SUBSTRUCTURES

M. Motylenko¹, M. Haberjahn², P. Klimanek¹, M. Masimov¹

¹ Freiberg University of Mining and Technology, Institute of Physical Metallurgy, D – 09596 Freiberg/Sa. Germany
² Infineon Technologies AG, D – 01 109 Dresden, Germany

A detailed description of complex deformation – induced substructures (Fig. 1) in both single crystals and polycrystalline materials requires the use of different methods of investigation, realizing the microstructure analysis on different length and volume scales, respectively. An important tool for this purpose is the combined use of electron microscopy and X – dif-fraction. The application of the techniques is demonstrated by results obtained with [001] oriented Cu and Ni single crystals and polycrystalline a - brass CuZn23 after deformation by uniaxial compression up to strains e =1. For the analysis the following methods were applied:

· Transmission electron microscopy (TEM, e.g. [1]) for the direct imaging of the substructure and the identification of special lattice defects or defect configurations,

· Electron backscattering diffraction (EBSD, e. g. [2,3]) for the estimation of substructure parameters as the size and the misorientation of cell – blocks or subgrains from orientation maps of the sample surface, and

· X – ray diffractometry (XRD), which allows the determination of various characteristics of the dislocation structure (e.g. lattice strains and rotations related to the total dislocation content [4,5] and the density of excess dislocations stored in dislocation walls [3,6,7]) from the broadening of X – ray reflections.

In the single crystals both the TEM and the REM data describe the dislocation–induced sub-structure. In the polycrystalline material the REM data are influenced by twinning and the grain size, but if their effect is taken into account, very good agreement of the results of TEM and EBSD is obtained. Dislocation – induced lattice misorientations and densities of excess dislocations, respectively, can be determined in single crystals from the broadening of X – ray rocking curves as well as from EBSD orientation maps. In polycrystals only the application of EBSD is possible, because the measurement of rocking curves of individual crystallites by conventional X–diffractometry is usually impossible. It is therefore, important, that EBSD gives useful values of the dislocation – induced misorientations even at larger strains, where rotational deformation modes (Formation of disclinations) are activated.

[1] Klimanek, P., Klemm, V., Romanov, A. E., Seefeldt, M.: Adv. Eng. Mater. 3 (2001) 877 – 884

[2] Randle, V.: Microtexture Determination and Its Applications. Institute of Materials, London 1992

[3] Masimov, M., Klimanek, P., Motylenko, M.: Submitted to Scripta Mater.

[4] Krivoglaz M.A.: X-ray and Neutron Diffraction in Non-Ideal Crystals. Springer Verlag, Berlin – Heidelberg, 1996.

[5] Ungár T. in: Defect and microstructure analysis by diffraction. (Eds. R. Snyder, J. Fiala, H. – J. Bunge ), Oxford University Press, 2000.

[6] Breuer D., Klimanek P. and Pantleon W.: X-ray determination of dislocation densities and arrangement in plastically deformed cooper. J. Appl. Cryst. 33, (2000), pp.1284-1295.

[7] Barabash R.I. and Klimanek P.: X-ray scattering by crystals with local lattice-rotation fields. J. Appl. Cryst. 32, (1999), pp. 1050 – 1060.