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Materials science diffractometer
In response to the development of new materials and the application of materials and components in new technologies the direct measurement, calculation and evaluation of textures and residual stresses has gained worldwide significance in recent years.
STRESS-SPEC, the materials science diffractometer is located at the thermal beam port SR-3 of the FRM II and can easily be configured either for texture analysis or strain measurements.
The set-up utilises three different monochromators: Ge (511), bent silicon Si (400) and pyrolitic graphite PG(002). This selection of monochromators and the possibility to vary automatically the take-off angles from 2θM = 35º to 110º allows to find a good compromise between resolution and intensity for each measuring problem.
The gauge volume defining optical system of primary and secondary slits is designed with regard to reproducibility of geometrical alignment and sturdiness. Instead of the slits a set of radial collimators is available to define the gauge volume. Samples can be aligned using theodolites and a camera system. In addition, the possibility to scan surfaces of components offline using a CMM scanner is available at STRESS-SPEC.
 Hofmann, M. et al., Physica B, 385 386, 1035 1037 (2006).
 Saroun, J. et al., J. Appl. Cryst., 46, 628 638 (2013).
 Brokmeier, H.-G. et al., Nucl. Instr. Meth. A, 642, 1, 87 92 (2011).
A positioning system consisting of a Stäubli-6-axes robotic arm for texture and strain measurements (payload up to 30 kg) can be mounted instead of the standard sample table. It offers more flexibility than an Eulerian cradle and can be also used as automatic sample changer for texture measurements .
 Randau, C. et al., Nucl. Instr. Meth. A, 794, 67–75 (2015).
STeCa is the standard software tool to analyse the 2D-detcetor data of STRESS-SPEC. Besides display functionalities, various functions for integration and Bragg peak refinement are available. In addition, one can generate and visualise the pole figures from texture measurements. The software is available for Linux or Windows and can be downloaded from the web page of the Computing Group
DISEMM (Diffraction assisted mechanical modeling) 
The software DISEMM is designed to analyse diffraction data from in-situ loading experiments to obtain diffraction elastic constants and single-crystal elastic constants as well as to describe the mechanical behavior by the elasto-plastic self –consistent modeling. DISEMM offers a variety of grain-to-grain interaction models, integrates texture and multi-phase alloys. The software is currently available for Windows. The DISEMM software can be downloaded here, with the corresponding manual here.
STRESSFIT is a Python package for fitting of neutron residual strain scanning data. The primary objective is to restore intrinsic lattice strain distributions measured by neutron diffraction. In an experiment, this distribution is smeared by finite spatial resolution of the instrument. Measured strains are also affected by so called pseudo-strains, which arise in general from inhomogeneous sampling of the material. The best known is the surface effect, when the nominal gauge volume of the instrument is only partly immersed under the sample surface. this gives rise to peak shifts (pseudo strains) of similar magnitude as the intrinsic strain.
The Python package can be found here as well as the respective available documentation.
 Randau, C. et al., J. Appl. Cryst., 44, 641-646 (2011).
 Heldmann, A. et al., J. Appl. Cryst., 52, 1144-1156 (2019).
 Šaroun, J. et al., Phys. Rev. B Condens. Matter, 551, 468-471 (2018).
Dr. Michael Hofmann
Phone: +49 (0)89 289-14744
Dr. Weimin Gan
Phone: +49 (0)89 158860-766
Phone: +49 (0)89 289-14814
Find the latest publications regarding STRESS-SPEC in our publication database iMPULSE:
Heinz Maier-Leibnitz Zentrum. (2015). STRESS-SPEC: Materials science diffractometer. Journal of large-scale research facilities, 1, A6. http://dx.doi.org/10.17815/jlsrf-1-25
For citation please always include the DOI.