Ulf Garbe

Texture analysis with high-energy synchrotron radiation

Texture measurement with short-wave X-ray synchrotron radiation in the range of λ ≃ 0.1 A is described. The measurements were carried out with the multipurpose diffraction instrument at the high-field wiggler, high-energy beamline BW5 at HASYLAB. The instrument was equipped with an on-line image-plate area detector for diffraction-image registration and a Eulerian cradle for sample orientation. The particular features of texture measurement with the BW5 instrument are: good resolution in the Bragg angle, extremely high angular resolution in crystal orientation (pole-figure angles) and particularly high penetration depth of several millimetres to centimetres, comparable with that of neutrons but at high spatial resolution. Several examples illustrate the particular advantages of this method for texture studies using large or encased samples (in situ studies in complicated environments, such as cryostats, furnaces, vacuum or pressure chambers, with no serious window problems). This allows, among others, non-destructive texture analysis in technological parts and whole components. Because of the extremely high beam intensity (short exposure times) compared with all other methods of texture measurement, the new technique is particularly suited for the study of large sample series (as is often necessary in industrial applications).

The Strain-Scanning Diffractometer Kowari

Residual stress has a crucial significance, especially for critical applications such as structural components of airplanes, in the pipeline industry, for welding technology, etc. Stress is introduced during the manufacturing of components or during their service life and can be beneficial or can have a negative impact on the mechanical integrity of components. When it comes to control or experimental assessment of these components, the neutron residual-stress diffractometer is an indispensable tool for non-destructive examination. Using the high penetration of thermal neutrons and a special design the stress instruments can measure distortions of the crystal lattice as accurate as ∼10−5 Å for d∼1 Å.

Texture and microstructure analysis with high-energy synchrotron radiation

High-energy synchrotron radiation with wavelengths in the range of 0.1 A is an excellent tool to measure the orientational and spatial distribution of crystallites in polycrystalline materials of any kind. A particular sweeping method for continuous imaging of texture and microstructure with high resolving power is described. In grain-resolved structures, the orientation stereology of the grains can thus be obtained. High-energy synchrotron radiation has penetration depths in most materials comparable with that of neutrons. It is thus very well suited for the study of big samples and for non-destructive testing of complex technological components.

Microstructure and texture analysis of δ-hydride precipitation in Zircaloy-4 materials by electron microscopy and neutron diffraction

This work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated δ-ZrH1.66 generally follows the δ(111)//α(0001) and δ[1{\overline 1}0]//α[11{\overline 2}0] orientation relationship with the α-Zr matrix. The δ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and δ-hydride. Neutron diffraction line profile analysis and high-resolution transmission electron microscopy observations reveal a significant number of dislocations present in the δ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α-Zr matrix. The present observations provide an insight into the behaviour of δ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides.

Kowari - OPAL's New Stress Diffractometer for the Engineering Community: Capabilities and First Results

Kowari is a neutron diffractometer at ANSTO’s research reactor OPAL. The instrument is dedicated to investigate residual strains and stresses in engineering samples or new materials. Besides its usage in engineering/strain-scanning it is more and more frequently being used for obtaining texture information related to materials science applications. In particular the possibility of using the gauge volume defining slit systems allows extracting local information from the diffraction peak, i.e. position, intensity, and width, without the need to cut the sample specimen. The instrument obtained its operating license in August 2008 to briefly describe the instruments parameters and capabilities, and give examples of two typical applications since it went from commissioning into user mode.

DINGO – the neutron imaging station at ANSTO: embracing material science, palaeontology, and cultural heritage

Volume 27 • Number 2 • 2016 Neutron News 14 Introduction After one year of hot commissioning, Australia jumped to the forefront of neutron imaging with the startup of the instrument DINGO on the OPAL reactor at ANSTO in early 2014. With barely a dozen neutron imaging stations world-wide, this brought the much-needed capability of state-of-the-art neutron radiography and neutron tomography setups [1, 2] to the Asia-Oceania region. Acquisition speed and spatial resolution can be tuned by choosing amongst different sets of apertures, scintillation screens, and detector systems to meet the needs of the broad user community. Researchers, curators, and industrial clients now have access to one of the highest-intensity neutron-imaging instruments in the world, able to obtain detailed radiographs of scientifi c objects, museum artefacts, and engineering pieces in seconds to minutes, three-dimensional tomographs in several hours, and movies of processes such as running engines or motors, and the fl ow of fl uids in fuel cells, all non-destructively.

Effect of thermomechanical processing on the microstructure and retained austenite stability during in situ tensile testing using synchrotron X-Ray diffraction of NbMoAl TRIP steel

In this work we compare and contrast the stability of retained austenite during tensile testing of Nb-Mo-Al transformation-induced plasticity steel subjected to different thermomechanical processing schedules. The obtained microstructures were characterised using optical metallography, transmission electron microscopy and X-ray diffraction. The transformation of retained austenite to martensite under tensile loading was observed by in-situ high energy X-ray diffraction at 1ID / APS. It has been shown that the variations in the microstructure of the steel, such as volume fractions of present phases, their morphology and dimensions, play a critical role in the strain-induced transition of retained austenite to martensite.

Neutron scanning reveals unexpected complexity in the enamel thickness of an herbivorous Jurassic reptile

Eilenodontines are one of the oldest radiation of herbivorous lepidosaurs (snakes, lizards and tuatara) characterized by batteries of wide teeth with thick enamel that bear mammal-like wear facets. Unlike most reptiles, eilenodontines have limited tooth replacement, making dental longevity particularly important to them. We use both X-ray and neutron computed tomography to examine a fossil tooth from the eilenodontine Eilenodon (Late Jurassic, USA). Of the two approaches, neutron tomography was more successful and facilitated measurements of enamel thickness and distribution. We find the enamel thickness to be regionally variable, thin near the cusp tip (0.10 mm) but thicker around the base (0.15–0.30 mm) and notably greater than that of other rhynchocephalians such as the extant Sphenodon (0.08–0.14 mm). The thick enamel in Eilenodon would permit greater loading, extend tooth lifespan and facilitate the establishment of wear facets that have sharp edges for orally processing plant material such as horsetails (Equisetum). The shape of the enamel dentine junction indicates that tooth development in Eilenodon and Sphenodon involved similar folding of the epithelium but different ameloblast activity.

Using neutron tomography to examine guitar strings

Alison Jeanine Edwards1, Ulf Garbe1, Filomena Salvemini1, Ciaran F Edwards-McKeown2, John Close3, Peter Tregear4 1Australian Centre For Neutron Scattering, Australian Nuclear Science And Technol, Lucas Heights, Australia, 2Arthur St, Marrickville, Australia, 3Department of Quantum Science, Physics Education Centre, Australian National University, A.C.T., Australia, 4Department of Music, Royal Holloway University of London, Egham,Surrey, United Kingdom E-mail: Alisonedwar@gmail.com

Texture and Strain Experiments at OPAL

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. The determination of global texture and the local variation of texture for example by inhomogeneous deformation are very important due to the coherence between the texture and the physical and mechanical properties of materials.