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4,899 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I07-Surface & interface diffraction	Understanding passive film degradation and its effect on hydrogen embrittlement of super duplex stainless steel - Synchrotron X-ray and electrochemical measurements combined with CalPhaD and ab-initio computational studies Cem Ornek , Fan Zhang , Alfred Larsson , Mubashir Mansoor , Gary S. Harlow , Robin Kroll , Francesco Carla , Hadeel Hussain , Dirk L. Engelberg , Bora Derin , Jinshan Pan Applied Surface Science 628 DOI: 10.1016/j.apsusc.2023.157364 Diamond Proposal Number(s): [23388] Open Access Show Abstract ▼ Abstract: The passive film stability on stainless steel can be affected by hydrogen absorption and lead to microstructure embrittlement. This work shows that the absorption of hydrogen results in surface degradation due to oxide reduction and ionic defect generation within the passive film, which decomposes and eventually vanishes. The passive film provides a barrier to entering hydrogen, but when hydrogen is formed, atomic hydrogen infuses into the lattices of the austenite and ferrite phases, causing strain evolution, as shown by synchrotron x-ray diffraction data. The vacancy concentration and hence the strains increase with increasing electrochemical cathodic polarization. Under cathodic polarization, the surface oxides are thermodynamically unstable, but the complete reduction is kinetically restrained. As a result, surface oxides remain present under excessive cathodic polarization, contesting the classical assumption that oxides are easily removed. Density-functional theory calculations have shown that the degradation of the passive film is a reduction sequence of iron and chromium oxide, which causes thinning and change of the semiconductor properties of the passive film from n-type to p-type. As a result, the surface loses its passivity after long cathodic polarization and becomes only a weak barrier to hydrogen absorption and hence hydrogen embrittlement.	Aug 2023
B18-Core EXAFS	Mild hydrogenolysis of lignin model compound and organosolv lignin over non-noble bimetallic Ni–Fe/TiN catalyst Tang Son Nguyen , Manh Tu Le , Van Hieu Nguyen Biomass And Bioenergy 174 DOI: 10.1016/j.biombioe.2023.106821 Diamond Proposal Number(s): [15151] Show Abstract ▼ Abstract: Lignin is one of the most promising feedstocks for renewable aromatics production. Conversion of such feedstock into aromatics can be attained through catalytic hydrogenolysis. In this work, NixFey/TiN bimetallic catalysts were evaluated in the hydrogenolysis of both: (i) benzyl phenyl ether (BPE) as a model compound for lignin and (ii) real organosolv lignin feedstock under low temperature (150 °C) and low H2 pressure (12 bar). All bimetallic catalysts exhibited superior performance over single-component materials and were shown to compose of uniformly/highly dispersed and intimately mixed Ni and Fe nanoparticles. Among bimetallic materials, Ni5Fe2/TiN possesses the highest activity in BPE hydrogenolysis, which is comparable to that of a 5% Pd/C commercial catalyst while showing significantly higher aromatic selectivity. Ni5Fe2/TiN catalyst also outperformed Pd/C in hydrogenolysis of organosolv lignin, shown by its higher oil yield, greater content of phenolic monomers, and lower content of dimers. This material exhibited good stability in BPE conversion with no noticeable deactivation over 5 recycling cycles. XANES analysis suggests the electron transfer from Ni to Fe, which explains the superior activity observed with Ni5Fe2/TiN.	Jul 2023
I10-Beamline for Advanced Dichroism	X-ray detected ferromagnetic resonance techniques for the study of magnetization dynamics Gerrit Van Der Laan , Thorsten Hesjedal Nuclear Instruments And Methods In Physics Research Section B: Beam Interactions With Materials And Atoms 540, 85 - 93 DOI: 10.1016/j.nimb.2023.04.005 Open Access Show Abstract ▼ Abstract: Element-specific spectroscopies using synchrotron-radiation can provide unique insights into materials properties. The recently developed technique of X-ray detected ferromagnetic resonance (XFMR) allows studying the magnetization dynamics of magnetic spin structures. Magnetic sensitivity in XFMR is obtained from the X-ray magnetic circular dichroism (XMCD) effect, where the phase of the magnetization precession of each magnetic layer with respect to the exciting radio frequency is obtained using stroboscopic probing of the spin precession. Measurement of both amplitude and phase response in the magnetic layers as a function of bias field can give a clear signature of spin-transfer torque (STT) coupling between ferromagnetic layers due to spin pumping. In the last few years, there have been new developments utilizing X-ray scattering techniques to reveal the precessional magnetization dynamics of ordered spin structures in the GHz frequency range. The techniques of diffraction and reflectometry ferromagnetic resonance (DFMR and RFMR) provide novel ways for the probing of the dynamics of chiral and multilayered magnetic materials, thereby accessing key information relevant to the engineering and development of high-density and low-energy consumption data processing solutions.	Jul 2023
I11-High Resolution Powder Diffraction	Characterisation of residual stresses and oxides in titanium, nickel, and aluminium alloy additive manufacturing powders via synchrotron X-ray diffraction Max D.a. Valentine , Vimal Dhokia , Joseph Flynn , Sophie A. M. Mcnair , Alexander J. G. Lunt Materials Today Communications 35 DOI: 10.1016/j.mtcomm.2023.105900 Diamond Proposal Number(s): [23975] Show Abstract ▼ Abstract: The strength and fracture toughness of Additively Manufactured (AM) components are significantly influenced by the concentration and size of oxides and precipitate inclusions within the build powders. These features are highly sensitive to powder production parameters, as well as the number of times a powder has been reused. In this study synchrotron X-ray powder diffraction was performed in an inert atmosphere at room temperature and during in-situ heating, providing crucial insights into growth rates and distribution of oxides and precipitates as a function of temperature. From the high angular resolution data collected, the structural refinement showed that plasma wire arc atomisation shows lower residual strain than gas atomised powder samples at room temperature after atomisation likely due to lower temperatures achieved during the production process. Additionally, the results from the diffraction patterns collected during in-situ heating provide key insights to the four metal powders considered in this study, Ti-6Al-4 V, Ni718, AlSi10Mg, and Scalmalloy. This paper also highlights the potential that using synchrotron X-ray diffraction to study AM parts and constituent AM powder has to gain crucial insight into material properties and the build reliability of end use production quality parts from AM.	Jun 2023
I12-JEEP: Joint Engineering, Environmental and Processing	Thermoelectric magnetohydrodynamic control of melt pool flow during laser directed energy deposition additive manufacturing Xianqiang Fan , Tristan G. Fleming , David T. Rees , Yuze Huang , Sebastian Marussi , Chu Lun Alex Leung , Robert C. Atwood , Andrew Kao , Peter D. Lee Additive Manufacturing 71 DOI: 10.1016/j.addma.2023.103587 Diamond Proposal Number(s): [28804] Open Access Show Abstract ▼ Abstract: Melt flow is critical to build quality during additive manufacturing (AM). When an external magnetic field is applied, it causes forces that alter the flow through the thermoelectric magnetohydrodynamic (TEMHD) effect, potentially altering the final microstructure. However, the extent of TEMHD forces and their underlying mechanisms, remain unclear. We trace the flow of tungsten particles using in situ high-speed synchrotron X-ray radiography and ex situ tomography to reveal the structure of TEMHD-induced flow during directed energy deposition AM (DED-AM). When no magnetic field is imposed, Marangoni convection dominates the flow, leading to a relatively even particle distribution. With a magnetic field parallel to the scan direction, TEMHD flow is induced, circulating in the cross-sectional plane, causing particle segregation to the bottom and side of the pool. Further, a downward magnetic field causes horizontal circulation, segregating particles to the other side. Our results demonstrate that TEMHD can disrupt melt pool flow during DED-AM.	Jun 2023
I07-Surface & interface diffraction	The causation of hydrogen embrittlement of duplex stainless steel: Phase instability of the austenite phase and ductile-to-brittle transition of the ferrite phase – Synergy between experiments and modelling Cem Ornek , Mubashir Mansoor , Alfred Larsson , Fan Zhang , Gary S. Harlow , Robin Kroll , Francesco Carla , Hadeel Hussain , Bora Derin , Ulf Kivisäkk , Dirk L. Engelberg , Edvin Lundgren , Jinshan Pan Corrosion Science 217 DOI: 10.1016/j.corsci.2023.111140 Diamond Proposal Number(s): [23388] Open Access Show Abstract ▼ Abstract: Various mechanisms have been proposed for hydrogen embrittlement of duplex stainless steel, but the causation of hydrogen-induced material degradation has remained unclear. This work shows that phase instability (decomposition) of the austenite phase and ductile-to-brittle transition of the ferrite phase precedes hydrogen embrittlement. In-situ diffraction measurements revealed that Ni-rich sites of the austenite phase decompose into metastable hydrides. Hydride formation is possible by increasing the hydrogen chemical potential during electrochemical charging and low defect formation energy of hydrogen interstitials. Our findings demonstrate that hydrogen embrittlement can only be understood if measured in situ and in real-time during the embrittlement process.	Jun 2023
I11-High Resolution Powder Diffraction	Controlling the magnetic structure in W-type hexaferrites Mathias I. Mørch , Mogens Christensen Journal Of Applied Crystallography 56 DOI: 10.1107/S1600576723002133 Diamond Proposal Number(s): [24845] Open Access Show Abstract ▼ Abstract: W-type hexaferrites with varied Co/Zn ratios were synthesized and the magnetic order was investigated using neutron powder diffraction. In SrCo2Fe16O27 and SrCoZnFe16O27 a planar (Cm′cm′) magnetic ordering was found, rather than the uniaxial ordering (P63/mm′c′) found in SrZn2Fe16O27 which is common in most W-type hexaferrites. In all three studied samples, non-collinear terms were present in the magnetic ordering. One of the non-collinear terms is common to the planar ordering in SrCoZnFe16O27 and uniaxial ordering in SrZn2Fe16O27, which could be a sign of an imminent transition in the magnetic structure. The thermomagnetic measurements revealed magnetic transitions at 520 and 360 K for SrCo2Fe16O27 and SrCoZnFe16O27, and Curie temperatures of 780 and 680 K, respectively, while SrZn2Fe16O27 showed no transition but a Curie temperature at 590 K. This leads to the conclusion that the magnetic transition can be adjusted by fine-tuning the Co/Zn stoichiometry in the sample.	Jun 2023
I12-JEEP: Joint Engineering, Environmental and Processing	3-Dimensional analysis of fatigue crack fields and crack growth by in situ synchrotron X-ray tomography A. Koko , S. Singh , S. Barhli , T. Connolley , N. T. Vo , T. Wigger , D. Liu , Y. Fu , J. Réthoré , J. Lechambre , J.-Y. Buffiere , T. J. Marrow International Journal Of Fatigue 170 DOI: 10.1016/j.ijfatigue.2023.107541 Diamond Proposal Number(s): [12585] Open Access Show Abstract ▼ Abstract: The propagation rate of a fatigue crack in a nodular cast iron, loaded in cyclic tension, has been studied in situ by X-ray computed tomography and digital volume correlation. The semi-elliptical crack initiated from an asymmetric corner notch and evolved to a semi-circular shape, initially with a higher growth rate towards one edge of the notch before the propagation rate along the crack front became essentially independent of po-sition. The phase congruency of the displacement field was used to measure the crack shape. The three-dimensional stress intensity factors were calculated via a linear elastic finite element model that used the displacement fields around the crack front as the boundary conditions. Closure of the crack tip region was observed. The cyclic change in the local mode I opening of the crack tip determined the local fatigue crack propaga-tion rate along the crack front.	May 2023
B18-Core EXAFS	Alternative reductants for foam control during vitrification of high-iron High Level Waste (HLW) feeds J. C. Rigby , D. R. Dixon , J. Kloužek , R. Pokorný , P. B. J. Thompson , A. Scrimshire , A. A. Kruger , A. M. T. Bell , P. A. Bingham Journal Of Non-Crystalline Solids 608 DOI: 10.1016/j.jnoncrysol.2023.122240 Diamond Proposal Number(s): [26801] Open Access Show Abstract ▼ Abstract: Foaming during vitrification of radioactive waste in Joule-Heated Ceramic Melters (JHCM) is exacerbated by trapping of evolving gases, such as CO2, NOx and O2, beneath a viscous reaction layer. Foaming restricts heat transfer during melting. Sucrose is employed as the baseline additive at the Hanford site in Washington State, USA to reduce foaming. Alternative carbon-based reductant additives were explored in simulated, inactive Hanford high-iron HLW-NG-Fe2 feeds, for both their effect on foaming and to give insight to the behaviour of multivalent species in glass melts under different redox conditions. Graphite, coke (93% C), formic acid and HEDTA additives were compared with sucrose, and a feed with no additive. Graphite and coke additions proved most effective in reducing the maximum foam volume by 51 ± 3% and 54 ± 2%, respectively, compared with 24 ± 5% for sucrose. Lower foaming could result in more efficient vitrification in JHCMs. Reductants also affected redox ratios in the multivalent species present in the feed. The order of reduction, Mn3+/Mn2+ > Cr6+/Cr3+ > Ce3+/Ce4+ > Fe3+/Fe2+ was as predicted on the basis of their redox potentials. There is less reduction overall, particularly in the Fe3+ → Fe2+, than predicted by the calculations, attributed to the oxygenated atmosphere of the experiments.	May 2023
	Multi-dimensional characterization of battery materials Ralf F. Ziesche , Thomas M. M. Heenan , Pooja Kumari , Jarrod Williams , Weiqun Li , Matthew E. Curd , Timothy L. Burnett , Ian Robinson , Dan J. L. Brett , Matthias J. Ehrhardt , Paul D. Quinn , Layla B. Mehdi , Philip J. Withers , Melanie Britton , Nigel D. Browning , Paul R. Shearing Advanced Energy Materials 101 DOI: 10.1002/aenm.202300103 Open Access Show Abstract ▼ Abstract: Demand for low carbon energy storage has highlighted the importance of imaging techniques for the characterization of electrode microstructures to determine key parameters associated with battery manufacture, operation, degradation, and failure both for next generation lithium and other novel battery systems. Here, recent progress and literature highlights from magnetic resonance, neutron, X-ray, focused ion beam, scanning and transmission electron microscopy are summarized. Two major trends are identified: First, the use of multi-modal microscopy in a correlative fashion, providing contrast modes spanning length- and time-scales, and second, the application of machine learning to guide data collection and analysis, recognizing the role of these tools in evaluating large data streams from increasingly sophisticated imaging experiments.	May 2023

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