HUBER LEDDI eight circles, energy dispersive diffractometer

With the diffractometer LEDDI (lab energy dispersive diffraction) structure depth gradient analysis (residual stress, texture, microstructure) can be performed with white X-rays (polychromatic) within the surface near region of materials. Due to the complexity of the instrument it is not possible to operate this instrument without assistance. Booking the LEDDI diffractometer is only possible after prior consultation with the instrument responsible.

LEDDI 8-circle diffractometer

LEDDI 8-circle diffractometer

The LEDDI-diffractometer is an 8-circle diffractometer which was especially developed in a co-operation between the HZB and the company HUBER Diffraktiontechnik in Rimsting. It is operated in the energy dispersive mode of diffraction, making use of white X-rays generated by a long fine focus tungsten W-X-ray-tube.

The primary beam can be defined by collimators or a 300 µm monocapillary. The 8-circle diffractometer is equipped with a x-y-z translation table that is controlled by a laser and CCD camera system. The operation is possible in the vertical as well was in the horizontal plane. The inclination angle ψ between the surface normal and ghkl is adjusted by means of an Eulerian cradle. The Φ-rotation table inside the Eulerian cradle enables a sample rotation around the surface normal, whereas the ω-rotation table below the Eulerian cradle allows for a direct rotation around the diffraction vector.

The diffracted intensity is simultaneously recorded with two energy dispersive point detectors after passing  0.15°- soller slits which are placed in front of each detector. Both detectors are Si(Li) detectors from the company Baltic Scientific Instruments.

Measurement control is performed with the software Spec, for the residual stress evaluation MATHEMATICA®  4.0 program packages[1] are used which were developed in-house. The texture analysis is performed with the software Labotex®. For the microstructure analysis in-house developed software in MATLAB® can be used.

[1]     Ch. Genzel. Entwicklung eines Mess- und Auswerteverfahrens zur röntgenographischen Analyse des Eigenspannungszustandes im Oberflächenbereich vielkristalliner Werkstoffe. Habilitationsschrift, Humboldt-Universität zu Berlin, 2000.