I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[16771]
Open Access
Abstract: An experimental technique is described for the collection of time-resolved X-ray diffraction information from a complete commercial battery cell during discharging or charging cycles. The technique uses an 80 × 80 pixel 2D energy-discriminating detector in a pinhole camera geometry which can be used with a polychromatic X-ray source. The concept was proved in a synchrotron X-ray study of commercial alkaline Zn–MnO2 AA size cells. Importantly, no modification of the cell was required. The technique enabled spatial and temporal changes to be observed with a time resolution of 20 min (5 min of data collection with a 15 min wait between scans). Chemical changes in the cell determined from diffraction information were correlated with complementary X-ray tomography scans performed on similar cells from the same batch. The clearest results were for the spatial and temporal changes in the Zn anode. Spatially, there was a sequential transformation of Zn to ZnO in the direction from the separator towards the current collector. Temporally, it was possible to track the transformation of Zn to ZnO during the discharge and follow the corresponding changes in the cathode.
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Dec 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[22178]
Open Access
Abstract: An X-ray transparent experimental triaxial rock deformation apparatus, here named `Mjölnir', enables investigations of brittle-style rock deformation and failure, as well as coupled thermal, chemical and mechanical processes relevant to a range of Earth subsurface environments. Designed to operate with cylindrical samples up to 3.2 mm outside-diameter and up to 10 mm length, Mjölnir can attain up to 50 MPa confining pressure and in excess of 600 MPa axial load. The addition of heaters extends the experimental range to temperatures up to 140°C. Deployment of Mjolnir on synchrotron beamlines indicates that full 3D datasets may be acquired in a few seconds to a few minutes, meaning full 4D investigations of deformation processes can be undertaken. Mjölnir is constructed from readily available materials and components and complete technical drawings are included in the supporting information.
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Nov 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[19556]
Open Access
Abstract: Accidents with explosive materials are still too common over 150 years after the patenting of dynamite. The manner by which they transit from burn to detonation (Deflagration to Detonation Transition; DDT) after a random thermal event, such as an electrical arc, or by friction if a package is dropped, is by far the single biggest risk associated with explosives storage and use. However this is a particularly difficult process to observe and quantify. Thus there are no agreed and verified theoretical frameworks for the process and thus no comprehensive predictive modelling capabilities. Recent experiments conducted at the Diamond Synchrotron have yielded ground-breaking, time-resolved observations of DDT. They have pioneered new experimental techniques and opened a new area for fast imaging at synchrotrons. We illustrate critical processes that occur within burning to detonation revealed in this study. These provide a new framework for understanding processes operating and offer the means to handle this class of materials more safely.
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Nov 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[16096]
Abstract: Thermal shocks are an important incident in operation of a pressure vessel which can have a significant impact on the structural integrity of the vessel. Often experiments that consider the state of the vessel before and after the thermal shock are used to evaluate the effects of the thermal shock. The studies can be complemented by time-resolved numerical simulations, which may be validated against the final state of the vessel obtained experimentally, to infer the transient response of the material. The transient response is important as the material experiences the highest level of stress in a short period which can induce catastrophic failure. This paper reports time-resolved experimental quantification of strain in reactor pressure vessel material during thermal shock measured by in-situ synchrotron diffraction. Specimens were extracted from a plate of nuclear pressure vessel steel with a nickel alloy cladding deposited by overlay welding. The specimens, with and without cracks, were subjected to thermal loading by heating then rapidly quenching the cladding in cold water. Strains were measured during thermal loading at a point near the crack tip from which the stress state around the crack tip was calculated and compared with a transient finite element model of the experiment. It was found that the peak near-tip stress occurred within the first second after the onset of rapid cooling. It was demonstrated from experimental measurements that the peak stress intensity factor occurred during thermal shock, rather than under steady conditions before or after the thermal shock. It was shown that although the finite element simulation predicts the steady state condition of the material after thermal shock, its transient response dependents significantly on a number of inputs with high uncertainty, making its time-resolved results unreliable for high-fidelity integrity assessments.
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Oct 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Open Access
Abstract: The martensitic transformation in Ti-Nb alloys can result in superelastic and shape memory behaviour but significant discrepancies exist between the transformation conditions reported for a given composition. To elucidate the reasons for these variations, in situ synchrotron diffraction experiments have been performed on Ti-24Nb (at.%) in two different microstructural conditions. Markedly different transformation behaviour was observed between these two conditions, including fully reversible superelastic behaviour below the apparent martensitic start temperature. These results could not be rationalised using thermally based transformation descriptions. As such, a new approach is introduced based upon the total stress level in a material.
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Oct 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Open Access
Abstract: The superelastic behaviour of Ti-Nb alloys gives rise to properties that are attractive for specific applications in the biomedical and aerospace sectors. However, to date, industrial utilisation of these alloys has been limited due the inability to tailor the transformation conditions or achieve stable cyclic behaviour. Alloying is the primary method for modifying transformation conditions but significant variations exist between the results of different studies within the literature. Here, to try and provide increased clarity, the transformation behaviour of Ti-24Nb-(0-8)Ta and Zr (at.%) have been investigated using in situ synchrotron diffraction to directly assess the transformation behaviour of the alloys in response to both temperature and tensile loads. In contrast to previous reports, no evidence of the αʺ phase was found in any of the alloys when cooled from 350 to -196˚C. In addition, the β to αʺ transformation was observed to be reversible when loaded at both 30˚C and ‑196˚C. These observations suggest that β stability may be far greater than previously thought and requires a review of the current mechanistic understanding.
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Oct 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[17450]
Abstract: Amorphous solid dispersions (ASDs) of class II and IV biopharmaceutics classification system drugs in water-miscible polymers are a well-recognized means of enhancing dissolution, while such dispersions in hydrophobic polymers form the basis of micro- and nanoparticulate technologies. However, drug recrystallization presents significant problems for product development, and the mechanisms and pathways involved are poorly understood. Here, we outline the use of combined differential scanning calorimetry (DSC)-synchrotron X-ray diffraction to monitor the sequential appearance of polymorphs of olanzapine (OLZ) when dispersed in a range of polymers. In a recent study (Cryst. Growth Des.2019,19, 2751–2757), we reported a new polymorph (form IV) of OLZ which crystallized from a spray-dried dispersion of OLZ in polyvinylpyrrolidone. Here, we extend our earlier study to explore OLZ dispersions in poly(lactide-co-glycolide) (PLGA), polylactide (PLA), and hydroxypropyl methyl cellulose acetate succinate (HPMCAS), with a view to identifying the sequence of form generation on heating each dispersion. While spray-dried OLZ results in the formation of crystalline form I, the spray-dried material with HPMCAS comprises an ASD, and forms I and IV are generated upon heating. PLGA and PLA result in a product which contains both amorphous OLZ and the dichloromethane solvate; upon heating, the amorphous material converts to forms I, II, and IV and the solvate to forms I and II. Our data show that it is possible to quantitatively assess not only the polymorph generation sequence but also the relative proportions as a function of temperature. Of particular note is that the sequence of form generation is significantly more complex than may be indicated by DSC data alone, with coincident generation of different polymorphs and complex interconversions as the material is heated. We argue that this may have implications not only for the mechanistic understanding of polymorph generation but also as an aid to identifying the range of polymorphic forms that may be produced by a single-drug molecule.
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Oct 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Open Access
Abstract: The microstructure of Ti-64 strongly affects the forming and in-service behaviour of aerospace components. The development of microstructure, including crystallographic texture, during thermomechanical processing involves changes caused by deformation, annealing and phase transformation. Recently, it has been reported that deformation and transformation occur concurrently, in a dynamic α → β transformation process, driven by the net flow softening it produces. Here, we present the results of an in-situ synchrotron diffraction experiment that aimed to detect and measure the extent of dynamic phase transformation during hot deformation and its contribution to the crystallographic texture of the alloy. Forged Ti-64 samples were deformed in uniaxial tension at 950°C and a strain rate of about 0.02 s-1, using an electro-thermal mechanical tester (ETMT) mounted on the I12: JEEP beamline at Diamond Light Source. By using a high energy 89 keV synchrotron X-ray beam and a fast acquisition rate (10 Hz) we were able to measure, during deformation, the internal elastic lattice strains in the two phases, the crystallographic texture of both phases and the α → β phase fraction. The results show, for the first time, direct evidence of dynamic transformation during isothermal hot deformation.
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Oct 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Katherine J.
Dobson
,
Anja
Allabar
,
Eloise
Bretagne
,
Jason
Coumans
,
Mike
Cassidy
,
Corrado
Cimarelli
,
Rebecca
Coats
,
Thomas
Connolley
,
Loic
Courtois
,
Donald B.
Dingwell
,
Danilo
Di Genova
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Benjamin
Fernando
,
Julie L.
Fife
,
Frey
Fyfe
,
Stephan
Gehne
,
Thomas
Jones
,
Jackie E.
Kendrick
,
Helen
Kinvig
,
Stephan
Kolzenburg
,
Yan
Lavallee
,
Emma
Liu
,
Edward W.
Llewellin
,
Amber
Madden-nadeau
,
Kamel
Madi
,
Federica
Marone
,
Cerith
Morgan
,
Julie
Oppenheimer
,
Anna
Ploszajski
,
Gavin
Reid
,
Jenny
Schauroth
,
Christian M.
Schlepütz
,
Catriona
Sellick
,
Jérémie
Vasseur
,
Felix W.
Von Aulock
,
Fabian B.
Wadsworth
,
Sebastian
Wiesmaier
,
Kaz
Wanelik
Diamond Proposal Number(s):
[15898]
Open Access
Abstract: Many of the grand challenges in volcanic and magmatic research are focused on understanding the dynamics of highly heterogeneous systems and the critical conditions that enable magmas to move or eruptions to initiate. From the formation and development of magma reservoirs, through propagation and arrest of magma, to the conditions in the conduit, gas escape, eruption dynamics, and beyond into the environmental impacts of that eruption, we are trying to define how processes occur, their rates and timings, and their causes and consequences. However, we are usually unable to observe the processes directly. Here we give a short synopsis of the new capabilities and highlight the potential insights that in situ observation can provide. We present the XRheo and Pele furnace experimental apparatus and analytical toolkit for the in situ X-ray tomography-based quantification of magmatic microstructural evolution during rheological testing. We present the first 3D data showing the evolving textural heterogeneity within a shearing magma, highlighting the dynamic changes to microstructure that occur from the initiation of shear, and the variability of the microstructural response to that shear as deformation progresses. The particular shear experiments highlighted here focus on the effect of shear on bubble coalescence with a view to shedding light on both magma transport and fragmentation processes. The XRheo system is intended to help us understand the microstructural controls on the complex and non-Newtonian evolution of magma rheology, and is therefore used to elucidate the many mobilization, transport, and eruption phenomena controlled by the rheological evolution of a multi-phase magmatic flows. The detailed, in situ characterization of sample textures presented here therefore represents the opening of a new field for the accurate parameterization of dynamic microstructural control on rheological behavior.
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Sep 2020
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[19662]
Abstract: Chemical short range order and topology of GexGaxTe100-2x glasses was investigated by neutron- and x-ray diffraction as well as Ge and Ga K-edge extended x-ray absorption fine structure (EXAFS) measurements. Large scale structural models were obtained by fitting experimental datasets simultaneously with the reverse Monte Carlo simulation technique. Models, relying only on experimental data and basic physical information without constraining the average coordination numbers, give 3.9–4.1 for the number of the atoms in the first coordination sphere of Ge atoms, while the average number of first neighbors of Ga atoms scatters around 3.8. The average coordination number of Te atoms is significantly higher than 2 for x = 12.5 and 14.3. It is found that the vast majority of MTe4 (M = Ge or Ga) tetrahedra have at least one corner sharing MTe4 neighbor.
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Sep 2020
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