Author: Ulf Garbe

Abstract
U. Garbe1, M. Hofmann2, J. Rebelo-Kornmeier and H.-G. Brokmeier3
1GKSS Forschungszentrum, Max-Planck-Str. 1, D-21502 Geesthacht, Germany
2FRM-II, TU München, Lichtenbergstr. 1, D-85747 Garching, Germany
3Institut für Werkstoffkunde und Werkstofftechnik der Technischen Universität Clausthal, Agricolastr. 6, D-38678 Clausthal- Zellerfeld, Germany.

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. Non-destructive analysis for phase specific residual stresses and textures is only possible by means of diffraction methods.

In order to cater for the development of these analytical techniques the new Materials Science Diffractometer STRESS-SPEC at FRM-II is designed to be equally applied to texture or residual stress analyses by virtue of its flexible configuration. The system compromises a highly flexible monochromator setup using three different monochromators: Ge (511), bent silicon and pyrolitic graphite (002). This range of monochromators and the possibility to vary the take-off angles from 2theta_M = 30º to 120º allows wavelength adjustment such that measurements can be performed around a scattering angle of 2theta_S ~ 90º. This is important in order to optimise neutron flux and resolution, especially for stress analysis on components, since the gauge volume element in that case is cubic and large vertical divergences due to focusing monochromators do not affect the spatial resolution.

The instrument is now available for routine operation and here we will present full details of first experiments and instrument performance. We present some examples of those experiments to comission and test the capabilities of STRESS-SPEC during the first reactor cycle of the new research reactor FRM-II in Munich will be presented.

The first pole figures measured on STRESS-SPEC using standard sample show that global texture analysis is feasible [2]. The results and also the time required to measure the pole figures are comparable to measurements at the dedicated texture diffractometer TEX-2 [3]. Our experiments, however, show that in future due to the high neutron flux at STRESS-SPEC in combination with the area detector it will be possible to decrease the data acquisition time by a factor of 3. The performance of the beamline leads to another measurement technique. The combination of the strain measurement setup with the texture setup is a good tool for local texture measurement with a gauge volume 2*2*2mm.
References
[1] M. Hofmann, R.Schneider, G.A. Seidl, J. Rebelo-Kornmeier, R.C. Wimpory, U. Garbe and H.-G. Brokmeier, Physica B (2006) in press
[2] H.J. Bunge, H.R. Wenk, J. Pannetier, Neutron Diffraction Texture Analysis, Texture Microstruct.5 (1982) 153.
[3] H.-G. Brokmeier, U. Zink, R. Schnieber a. B. Wittassek, TEX-2. Texture Analysis at GKSS Research Center (Instrumentation and Application), Materials Sciences Forum 273-275 (1998), 277.