STRESS-SPEC

The Helmholtz-Zentrum Geesthacht and the Technical University of Clausthal (Prof. H.-G. Brokmeier) contribute with their texture competence to the operation of STRESS-SPEC at the FRM II together with TUM. STRESS-SPEC is unique in its capability for strain and texture measurements with high local resolution on large volume samples and components.

The determination of the local variation of texture for example by inhomogeneous deformation is very important, due to the coherence between the texture and the physical and mechanical properties of materials. Therefore, a new measurement technique for local texture analyses with neutron radiation was developed. First measurements of local texture [1] have shown that the established method of strain measurement with neutron radiation at STRESS-SPEC [2-3] also provides a good basis for local texture analysis. Due to the flexible configuration it is possible to reduce the data acquisition time for every local pole figure down to 5 hours.

With further planned improvements of the beamline using focussing neutron optics and a larger detection area it is expected to reduce the data collection time further. The possibility to take data with two or three position sensitive detectors in combination with a focussing parabolic neutron guide has been calculated. These calculations show that in comparison with the existing setup it is possible to reduce the number of measured orientations more than three times. The neutron guide leads to three times higher flux at the sample position.

Funded by a recently started BMBF Verbundforschung project, the existing Eulerian cradle, which is limited in sample size and translation, will be replaced by a more flexible robotic system (Fig. 1). The robot can be used simultaneously for automatic sample manipulation and sample change. It will also allow faster alignment and positioning of larger samples. The combination of the focusing neutron guide with three area detectors and the robotic system enables 3-D texture mapping in acceptable timescales.