Abstract: Additional to the position of any volume element of a (poly)-crystalline material its crystal orientation must also be known. Both together are described in the six-dimensional orientation-location space. The paper describes the most frequent structures of materials in this space and how these can be imaged with the "Moving Area Detector Method" using hard synchrotron X-rays. This technique is equally well suited for basic reseach in materials science as well as for non-destructive testing of technological parts or even complex structural components.
Abstract: This paper focus on the use of orientation stereology to understand polycrystalline materials behavior. First some cautions or limits by using this approach are considered. Examples related to phase transformation, plastic deformation or crack propagation are then presented.
Abstract: In this work the textures of MgAl9Zn1, MgAl6Zn1, MgAl3Zn1 and MgAl2Mn alloys have been studied, using individual grain orientation measurement (“ACOM”) in the SEM. Hot extruded billets, unidirectional, reverse and cross-rolled sheet metals as well as laser welding seams have been investigated. In the shaft of a partial extrudate through a circular die orifice, a <0001> ring fiber texture has formed which continuously changes into a spiral fiber texture in the bottom neck. The unidirectional and the reverse hot rolled MgAl2Mn specimens show an R type <0001> texture with a small asymmetrical split whereby the basal poles are tilted by about ±12° from the sheet normal direction to the rolling direction. In the hot cross rolled specimens, the basal poles are slightly spread both in the first and second rolling directions. Texture in the laser welding seams is weak and distinctly different from that of the sheet material. There is almost no heat affected zone at the margins of the welding seams.
Abstract: The formation of the Goss texture in electrical steels is one of the most distinct phenomena of texture research. Nevertheless, disregarding 60 years of research the mechanisms which let only Goss-oriented grains grow abnormally during a secondary recrystallisation annealing are still not completely understood. The present paper reviews some of the mechanisms of growth selection and oriented nucleation and discusses them in the light of observations made by the authors. We conclude that no mechanism proposed so far is able to explain all experimental observations. This points out the need for the search for a different mechanism.
Abstract: The paper is an account of TEM based automatic orientation mapping summarizing more than two years of using the system. Following a brief introduction of the system elements, some representative applications are described. We focus on the characterization of fine-grain materials, mapping of low symmetry materials (metastable chromium carbide) and semi-automatic analysis of misorientations in a fully lamellar polycrystalline (g+a2) TiAl alloy. Moreover, the current state of the TEM based system is discussed and compared to EBSD systems. In particular, the issues of spatial resolution, accuracy, map acquisition time, reliability are considered.
Abstract: The 3 Dimensional X-Ray Diffraction (3DXRD) method is presented and its potentials illustrated by examples. The 3DXRD method is based on diffraction of high energy X-rays and allows fast and nondestructive 3D characterization of the local distribution of crystallographic orientations in the bulk. The spatial resolution is about 1x5x5 µm but diffraction from microstructural elements as small as 100 nm may be monitored within suitable samples. As examples of the use of the 3DXRD method, it is chosen to present results for complete 3D characterization of grain structures, in-situ “filming” of the growth of one interior grain during recrystallization, recrystallization kinetics of individual grains and crystallographic rotations of individual grains during tensile deformation.
Abstract: Due to the high penetration power, the high photon flux and the excellent brilliance high energetic synchrotron radiations are a phantastic tool particular in fast experimentation. Therefore in-situ measurements under applied load or at various temperatures have been carried out to investigate the texture influence on the deformation of magnesium and aluminium. An upgraded loading device with a power up to 20 kN was installed at the hard wiggler beamline BW5. Magnesium samples with different initial textures show the strong influence on this texture on the activation of different glide systems and on the activation of twins. First experiments to study the phase transition in titanium were performed, which demonstrate the strong orientation correlation between the α- and the β-phase.
Abstract: This paper describes the modernized diffractometer EPSILON-MDS for strain measurements of geological samples by means of neutron diffraction with the time-of-flight method. The diffractometer is characterized by a long flight path in order to get a good spectral resolution and by a multi-detector system for efficient data acquisition.