Texture and microstructure imaging in six dimensions with high-energy synchrotron radiation

The texture of a material can be calculated from several pole figures, which, in turn, are usually measured by one of several `step-scan' techniques. In these techniques, the finite step width limits the attainable orientation resolving power. In the present paper, the discontinuous step-scan technique is replaced by a continuous `sweeping' technique based on the continuous movement of an area detector during exposure. In this way, continuous two-dimensional `images' of pole figures are obtained, without the necessity of interpolation. Similar sweeping techniques are also being used to obtain continuous images of other sections and projections of the six-dimensional `orientation-location' space which characterizes a polycrystalline structure completely. The high potential orientation and/or location resolving power of these imaging techniques can only be reached with synchrotron radiation. In the present paper, the measurements were made at the high-energy (short-wavelength) beamline BW5 at HASYLAB/DESY in Hamburg. The high orientation and location resolving power implies the necessity to distinguish `grain-resolved' textures and microstructures (mainly in recrystallized materials) from `continuous' ones (mainly in deformed materials). Under certain conditions, it is thus possible to obtain the complete six-dimensional `orientation stereology' of grain-resolved microstructures. The new methods are illustrated with several examples, including technological applications.