Computer-aided crystallographic analysis in the TEM

doi:10.1016/S1076-5670(02)80019-2

Advances in Imaging and Electron Physics

Volume 125, 2003, Pages 355-415, II-XII

https://doi.org/10.1016/S1076-5670(02)80019-2 Get rights and content

Publisher Summary

This chapter presents the techniques for computer-aided crystallography in analytical transmission electron microscopy (TEM). The techniques include different methods for the semiautomated and completely automated determination of crystal orientations from different forms of electron diffraction patterns. The chapter discusses the analysis of different lattice defects like grain boundaries and dislocations. It presents the methods for the determination of crystal lattice parameters and for the calibration of microscope parameters. The concepts for the determination of crystal orientations are introduced and compared especially under the aspect of reaching the highest spatial resolution and orientation accuracy. Although the use of Kikuchi patterns is the most precise method, the use of spot patterns can be very interesting and becomes even indispensable in the case of orientation measurements in highly deformed metals. The accuracy of the spot pattern orientation determination can be much improved by taking into account the positions and intensities of the diffraction spots.

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We study the microstructure formation and mechanical properties of Ti-1Fe (wt%) and Ti-3Fe (wt%) alloys for different heat treatments in the β-phase and α + β-phase regions. By applying different heat treatment routes, we observe different microstructure formation mechanisms causing a wide range of mechanical properties from high strength (1.3 GPa) and low ductility (2%) to intermediate strength (700 MPa) and high ductility (30%) in these simple binary alloys.
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Furthermore, the site-specific observation of the deformation structures in the crack tip process zone is a major advantage, as this avoids any constraint relief artefacts that may result from TEM foil extraction at the crack tip. Accurate sample orientation information was obtained by EBSD at 70° to the sample surface normal and subsequent simulation of the electron channelling pattern (ECP) at 0° with software TOCA (Tools for Orientation Determination and Crystallographic Analysis) [42,43]. Any uncertainty in the orientation through misalignment of the EBSD system was corrected by a calibration of the ECP and EBSD patterns with single crystal Si.
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Therefore, the measured orientations allow for the determination of the three-dimensional extension of each twin boundary. Following a crystallographic analysis of all suitable twin boundaries using the TOCA software of S. Zaefferer [36,37], a single grain was chosen to be orientated into one of the three compression modes described in Table 1. This reorientation was accomplished by the use of custom sample holders that incorporate locating surfaces to fix the selected twin boundaries into the desired orientation, see Fig. 3b.
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Computer-aided crystallographic analysis in the TEM

Publisher Summary

Orientation imaging: The emergence of a new microscopy

Met. Trans.

Backscatter Kikuchi diffraction in the SEM for identification of crystallographic point groups

Scanning

A resolution of the interface phase problem in titanium alloys

Acta Metall.

X-ray scattering factors computed from numerical Hartree-Fock wave functions

Acta Cryst.

Determination of structure factors, lattice strains and accelerating voltage by energy filtered convergent beam electron diffraction

Ultramicroscopy

Software “ACT, Automated crystallography for the TEM”

Revised parameters of the analytic fits for coherent and incoherent scattered x-ray intensities of the first 36 atoms

Acta Cryst.

Methods and means for recognizing complex patterns

The determination of crystallographic textures from selected areas of a specimen by electron diffraction

Textures Microstructures

The relation between polycrystal deformation and single crystal deformation

Met. Trans.

Analysis of local strain in aluminium interconnects by energy filtered CBED

Ultramicroscopy

Using the Hough transform for HOLZ line identification in convergent beam electron diffraction

J. Microsc.

POWDER CELL, Programm zur Darstellung von Kristallstrukuren und Berechnung der zugehörigen Röntgendiffraktogramme für polykristalline Proben

Deutsche Bundesanstalt für Materialprüfung, Berlin

Automated determination of crystal orientations from electron backscattering patterns

Computerized analysis of Kikuchi patterns

A new procedure for automatic high precision measurements of the position and width of bands in backscatter Kikuchi patterns

A new procedure for automatic high precision measurements of the position and width of bands in backscatter Kikuchi patterns

Image processing procedures for analysis of electron diffraction patterns

Scanning Microsc.

Interface Sci.

Role of twinning in texture development and in plastic deformation of hexagonal materials

Textures Microstructures