TY - JOUR A1 - Beyer, Katrin A1 - Kannengießer, Thomas A1 - Griesche, Axel A1 - Schillinger, B. T1 - Neutron radiography study of hydrogen desorption in technical iron N2 - The purpose of the present study is to show the feasibility of examining hydrogen desorption in technical iron samples using neutron radiography at the ANTARES facility of the FRM II research reactor, Technische Universität München. It has been shown that this method is appropriate for in situ determination of hydrogen Desorption for concentrations as low as 20 ppmH. Experiments were carried out in the temperature range from room temperature up to 260 °C. Measurement was based on direct comparison between electrochemically hydrogen-loaded iron samples and hydrogen-free reference samples at the same temperature. This enables the determination of hydrogen concentration as a function of time and temperature. Ex situ carrier gas hot extraction experiments using the same temperature–time profiles as the neutron radiography experiments have been used to calibrate the greyscale values of the radiographs to defined hydrogen concentrations. It can be stated that hydrogen desorption correlates with sample temperature. KW - Neutron radiography KW - Hydrogen PY - 2011 U6 - https://doi.org/10.1007/s10853-011-5450-7 SN - 0022-2461 SN - 1573-4803 VL - 46 IS - 15 SP - 5171 EP - 5175 PB - Springer Science + Business Media B.V. CY - Norwell, Mass. AN - OPUS4-25150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Altenkirch, J. A1 - Gibmeier, J. A1 - Beyer, Katrin A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Welding problems - Investigations with neutrons of residual stress and of hydrogen diffusion in steels N2 - We report about investigations of typical material problems in steels. First, residual stresses in and around weld seams with low martensite transition temperature filler material were analyzed w/ and w/o additional transverse tensile load. The investigation was accompanied by x-ray diffraction measurements to track stress-induced phase transitions. Martensite formation during welding under external load yield strain gradients near the surface that improve the integrity of the weld. Further, the residual stress distribution close to laser-treated steel surfaces was analyzed. The method could be improved to reduce analysis artifacts. Finally, hydrogen diffusion in different steels was measured using neutron radiography and subsequent image analysis. Diffusion coefficients were derived by analyzing the time-dependent mass flux. In an outlook we describe the optimal ESS instrumentation from a metallurgist’s point of view. T2 - ESS Workshop "Science Vision for the European Spallation Source - German Perspectives" CY - Bad Reichenhall, Germany DA - 2011-10-10 PY - 2011 UR - http://www.fz-juelich.de/cae/servlet/contentblob/1058986/publicationFile/24649/Griesche_pdf.pdf UR - http://www.fz-juelich.de/sid_BD693DF17F42B3018726EE5C2558C56C/jcns/EN/Leistungen/ConferencesAndWorkshops/ESS/_node.html AN - OPUS4-24464 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heuskin, D. A1 - Kargl, F. A1 - Griesche, Axel A1 - Stenzel, C. A1 - Mitschke, D. A1 - Bräuer, D. A1 - Meyer, A. T1 - MSL compatible isothermal furnace insert for high temperature shear-cell diffusion experiments N2 - For long-time diffusion experiments shear-cell techniques offer more favourable terms than the traditional long capillary techniques. Here, we present a further developed shear-cell that enables the measurement of diffusion coefficients up to temperatures of 1600 °C. Hence, diffusion experiments can be carried out at temperatures not accessible until now by conventional capillary or shear-cell techniques. The modified shear-cell, which can contain up to six samples of a total length of 90mm and a diameter of 1.5 mm, is built of 30 shear discs of 3mm thickness each. It is operated in an isothermal furnace insert which can be accommodated in the Materials Science Laboratory of the International Space Station. This provides the opportunity that the shear-cell can be applied to microgravity and to ground-based experiments, respectively. The heater insert with an overall length of 518mm and a diameter of 210mm consists of four heating zones with a total power of 3.5 kW. Temperature homogeneity along the graphite sample compartment is better than 2K at 1600°C. Details of the new design are discussed and results of first successfully performed heating and shearing cycles are presented. KW - Microgravity KW - Diffusion KW - Shear cell KW - Melt KW - Alloy PY - 2011 U6 - https://doi.org/10.1088/1742-6596/327/1/012053 SN - 1742-6588 SN - 1742-6596 VL - 327 IS - 012053 SP - 1 EP - 8 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-24994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kargl, F. A1 - Engelhardt, M. A1 - Yang, F. A1 - Weis, H. A1 - Schmakat, P. A1 - Schillinger, B. A1 - Griesche, Axel A1 - Meyer, A. T1 - In situ studies of mass transport in liquid alloys by means of neutron radiography N2 - When in situ techniques became available in recent years this led to a breakthrough in accurately determining diffusion coefficients for liquid alloys. Here we discuss how neutron radiography can be used to measure chemical diffusion in a ternary AlCuAg alloy. Neutron radiography hereby gives complementary information to x-ray radiography used for measuring chemical diffusion and to quasielastic neutron scattering used mainly for determining self-diffusion. A novel Al2O3 based furnace that enables one to study diffusion processes by means of neutron radiography is discussed. A chemical diffusion coefficient of Ag against Al around the eutectic composition Al68.6Cu13.8Ag17.6 at.% was obtained. It is demonstrated that the in situ technique of neutron radiography is a powerful means to study mass transport properties in situ in binary and ternary alloys that show poor x-ray contrast. KW - Neutron radiography KW - Diffusion KW - Liquid alloys KW - Shear cell PY - 2011 U6 - https://doi.org/10.1088/0953-8984/23/25/254201 SN - 0953-8984 SN - 1361-648X VL - 23 IS - 25 SP - 254201-1 EP - 254201-8 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-23854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Beyer, Katrin A1 - Kannengießer, Thomas A1 - Griesche, Axel A1 - Schillinger, B. T1 - Study of hydrogen effusion in austenitic stainless steel by time-resolved in-situ measurements using neutron radiography N2 - The purpose of the present study was to show the feasibility of measuring hydrogen effusion in austenitic stainless steel (1.4301) using neutron radiography at the facility ANTARES of the research reactor FRM II of the Technische Universität München. This method is appropriate to measure in-situ hydrogen effusion for hydrogen concentrations as small as 20 ppmH. Experiments were carried out in the temperature range from room temperature up to 533 K. The measurement principle is based on the parallel comparison of electrochemically hydrogen charged specimen with hydrogen-free reference specimen at the same temperature. This allows the determination of the hydrogen concentration in the specimens as a function of time and temperature. Separate hot carrier gas extraction experiments using the same temperature–time profiles as the radiography experiments have been used to calibrate the grey values of the neutron transmission images into hydrogen concentrations. It can be stated that the hydrogen effusion correlates with the specimen temperature. KW - Hydrogen effusion KW - Austenitic stainless steels KW - Neutron radiography PY - 2011 U6 - https://doi.org/10.1016/j.nima.2011.02.010 SN - 0168-9002 SN - 0167-5087 VL - 651 IS - 1 SP - 211 EP - 215 PB - North-Holland CY - Amsterdam AN - OPUS4-23401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Horbach, J. A1 - Meyer, A. T1 - Influence of thermodynamic forces on diffusion in melts N2 - We report about diffusion measurements and molecular dynamic simulations in Al-Ni and Al-Cu melts. Capillary methods were used to measure Ni and Cu self diffusion and to measure interdiffusion. The combination of the capillary set-up with X-ray radiography allowed in-situ detecting of convective contributions to the interdiffusion transport by tracking the time dependence of diffusion. Thus, the determination of the interdiffusion coefficient can be restricted to convection-free experiment times resulting in an increased accuracy of the measured interdiffusion coefficient. Additionally, quasielastic neutron scattering was used to measure convection-free Ni and Cu self diffusion. Molecular dynamics simulations were used to determine all diffusion coefficients and the thermodynamic factor. The comparison between experiment and simulation shows an excellent agreement of the interdiffusion coefficients as a function of temperature. It was found that interdiffusion is enhanced by thermodynamic forces with a maximum around the stoichiometric composition. T2 - TMS 2011 CY - San Diego, CA, USA DA - 2011-02-27 PY - 2011 AN - OPUS4-23340 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel T1 - Diffusion of hydrogen in steels T2 - DLR-Seminar CY - Cologne, Germany DA - 2011-02-15 PY - 2011 AN - OPUS4-23341 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Griesche, Axel A1 - Beyer, Katrin A1 - Kannengießer, Thomas A1 - Solórzano, E. T1 - In-situ measurement of hydrogen diffusion in steels using neutron radiography T2 - DIMAT 2011, 8th International Conference On Diffusion In Materials CY - Dijon, France DA - 2011-07-03 PY - 2011 AN - OPUS4-24312 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -