TY - CHAP A1 - Griesche, Axel A1 - Große, M. A1 - Schillinger, B. ED - Fritzsche, H. ED - Huot, J. ED - Fruchart, D. T1 - Neutron imaging N2 - Neutron imaging methods are appropriate to investigate hydrogen distributions in several metallic systems. The large total neutron cross section of hydrogen compared to those of elements or isotopes, respectively, in usual structural materials like steels or zirconium alloys allows the detection even of small amounts of hydrogen in such materials. The dependence of the total macroscopic neutron cross section of the sample or component on the hydrogen concentration can be determined experimentally by means of calibration specimens with known hydrogen concentrations. Such a calibration allows for a full quantitative determination of the local hydrogen concentration with a spatial resolution better than 20 μm. Because neutron radiography is fast and non-destructive, in situ investigations of time-dependent processes like hydrogen absorption and release or hydrogen bulk diffusion can be performed. This chapter gives an introduction into the main neutron imaging methods, radiography and tomography, and gives as examples results of neutron imaging investigations of hydrogen in different steels and in zirconium alloys,respectively. KW - Neutron imaging KW - Neutron radiography KW - Hydrogen PY - 2016 SN - 978-3-319-22792-4 SN - 978-3-319-22791-7 U6 - https://doi.org/10.1007/978-3-319-22792-4_7 SN - 1868-0380 SN - 1868-0372 SP - Chapter 7, 193 EP - 225 PB - Springer Nature CY - Zurich, Switzerland AN - OPUS4-36365 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Browne, D. A1 - García-Moreno, F. A1 - Nguyen-Thi, H. A1 - Zimmermann, G. A1 - Kargl, F. A1 - Mathiesen, R. H. A1 - Griesche, Axel A1 - Minster, O. ED - Solanki, K. N. ED - Orlov, D. ED - Singh, A. ED - Neelameggham, N. R. T1 - Overview of In situ X-ray studies of light alloy solidification in microgravity N2 - Gravity has significant effects on alloy solidification, primarily due to thermosolutal convection and solid phase buoyancy. Since 2004, the European Space Agency has been supporting investigation of these effects by promoting in situ X-ray monitoring of the solidification of aluminium alloys on microgravity platforms, on earth, and in periodically varying g conditions. The first microgravity experiment-investigating foaming of liquid metals - was performed on board a sounding rocket, in 2008. In 2012 the first ever X-ray-monitored solidification of a fully dense metallic alloy in space was achieved: the focus was columnar solidification of an Al-Cu alloy. This was followed in 2015 by a similar experiment, investigating equiaxed solidification. Ground reference experiments were completed in all cases. In addition, experiments have been performed on board parabolic flights-where the effects of varying gravity have been studied. We review here the technical and scientific progress to date, and outline future perspectives. KW - Dendritic growth KW - Materials in space KW - Columnar and equiaxed structures PY - 2017 SN - 978-3-319-52392-7 SN - 978-3-319-52391-0 U6 - https://doi.org/10.1007/978-3-319-52392-7_80 SN - 2367-1181 SP - 581 EP - 590 PB - Springer CY - Berlin, Heidelberg AN - OPUS4-39442 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -