I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[19216]
Abstract: High-speed synchrotron tomography was used to investigate the nucleation and growth dynamics of Al13Fe4 intermetallic during solidification of an Al-5wt%Fe alloy, providing new insights into its formation process. The majority of Al13Fe4 intermetallics nucleated near the surface oxide of the specimen and a few nucleated at Al13Fe4 phase. Al13Fe4 crystals grew into a variety of shapes, including plate-like, hexagonal tabular, stair-like and V-shaped, which can be attributed to the crystal structure of this compound and its susceptibility to twinning. Hole-like defects filled with aluminium melt were observed within the intermetallics. Oriented particle attachment mechanism was proposed to explain the formation of the Al13Fe4 intermetallic, which needs further experiments and simulation to confirm.
|
Apr 2021
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
C.
Paraskevoulakos
,
J. P.
Forna-kreutzer
,
K. R.
Hallam
,
C. P.
Jones
,
T. B.
Scott
,
C.
Gausse
,
D. J.
Bailey
,
C. A.
Simpson
,
D.
Liu
,
C.
Reinhard
,
C. L.
Corkhill
,
M.
Mostafavi
Diamond Proposal Number(s):
[20189]
Open Access
Abstract: Decommissioning of the damaged Chernobyl nuclear reactor Unit 4 is a top priority for the global community. Before such operations begin, it is crucial to understand the behaviour of the hazardous materials formed during the accident. Since those materials formed under extreme and mostly unquantified conditions, modelling alone is insufficient to accurately predict their physical, chemical and, predominantly, mechanical behaviour. Meanwhile, knowledge of the mechanical characteristics of those materials, such as their strength, is a priority before robotic systems are employed for retrieval and the force expected from them to be exerted is one of the key design questions. In this paper we target to measurement of the standard mechanical properties of the materials formed during the accident by testing small-scale, low radioactivity simulants. A combined methodology using Hertzian indentation, synchrotron X-ray tomography and digital volume correlation (DVC), was adopted to estimate the mechanical properties. Displacement fields around the Hertzian indentation, performed in-situ in a synchrotron, were measured by analysing tomograms with DVC. The load applied during the indentation, combined with full-field displacement measured by DVC was used to estimate the mechanical properties, such as Young's modulus and Poisson's ratio of these hazardous materials.
|
Mar 2021
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[27011]
Abstract: A two-phase near-β titanium alloy (Ti–10V–2Fe–3Al, or Ti-1023) in its as-forged state is employed to illustrate the feasibility of a Bayesian framework to identify single-crystal elastic constants (SEC). High Energy X-ray diffraction (HE-XRD) obtained at the Diamond synchrotron source are used to characterize the evolution of lattice strains for various grain orientations during in situ specimen loading in the elastic regime. On the other hand, specimen behavior and grain deformation are estimated using the elastic self-consistent (ELSC) homogenization scheme. The XRD data and micromechanical modelling are revisited with a Bayesian framework. The effect of different material parameters (crystallographic and morphological textures, phase volume fraction) of the micromechanical model and the biases introduced by the XRD data on the identification of the SEC of the β phase are systematically investigated. In this respect, all the three cubic elastic constants of the β phase (
) in the Ti-1023 alloy have been derived with their uncertainties. The grain aspect ratio in the ELSC model, which is often not considered in the literature, is found to be an important parameter in affecting the identified SEC. The Bayesian inference suggests a high probability for non-spherical grains (aspect ratio of
):
. The uncertainty obtained by Bayesian approach lies in the range of ∼1-3 GPa for the shear modulus
, and ∼7 GPa for the shear modulus
, while it is significantly larger in the case of the bulk modulus
(∼17-24 GPa).
|
Feb 2021
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[24685]
Open Access
Abstract: This paper presents a diamond gammavoltaic cell – a solid state device which converts gamma radiation into electricity - with a novel design and promising capabilities. Gammavoltaics pose a unique challenge among radiovoltaics due to the highly penetrating nature of gamma rays. Adapting existing radiovoltaic and dosimeter designs by increasing their thickness risks throttling the flowing current, due to an attendant increase in series resistance. The presented design partially decouples this relationship, by creating a low-coverage hydrogen-terminated collection volume around the device, exploiting the transfer doping effect. This paper proves that hydrogen termination is necessary for the gammavoltaism exhibited. Data are then presented from current-voltage curves taken using synchrotron radiation, over the range 50 – 150 keV. A drop in series resistance over the range is discovered, and linked to the transition from the photoelectric effect to Compton scattering. The cell produces an open-circuit voltage VOC = 0.8 V. Its short-circuit current ISC and maximum power Pmax are found to also depend on photon energy, reaching maxima at ∼ 150 keV, where ISC > 10 μA and Pmax > 3 μW, normalised in flux to 2 × 1011 γ.s-1. Groundwork is hence laid for developing this type of cell for micropower applications.
|
Feb 2021
|
|
I11-High Resolution Powder Diffraction
I12-JEEP: Joint Engineering, Environmental and Processing
|
Kieran W. P.
Orr
,
Sean M.
Collins
,
Emily M.
Reynolds
,
Frank
Nightingale
,
Hanna L. B.
Bostroem
,
Simon J.
Cassidy
,
Daniel M.
Dawson
,
Sharon E.
Ashbrook
,
Oxana
Magdysyuk
,
Paul A.
Midgley
,
Andrew L.
Goodwin
,
Hamish H.-m.
Yeung
Diamond Proposal Number(s):
[20946, 18786]
Open Access
Abstract: Control over the spatial distribution of components in metal–organic frameworks has potential to unlock improved performance and new behaviour in separations, sensing and catalysis. We report an unprecedented single-step synthesis of multi-component metal–organic framework (MOF) nanoparticles based on the canonical ZIF-8 (Zn) system and its Cd analogue, which form with a core–shell structure whose internal interface can be systematically tuned. We use scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and a new composition gradient model to fit high-resolution X-ray diffraction data to show how core–shell composition and interface characteristics are intricately controlled by synthesis temperature and reaction composition. Particle formation is investigated by in situ X-ray diffraction, which reveals that the spatial distribution of components evolves with time and is determined by the interplay of phase stability, crystallisation kinetics and diffusion. This work opens up new possibilities for the control and characterisation of functionality, component distribution and interfaces in MOF-based materials.
|
Feb 2021
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
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.
|
Dec 2020
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
W. U.
Mirihanage
,
J. D.
Robson
,
S.
Mishra
,
P.
Hidalgo-manrique
,
J.
Quinta Da Fonseca
,
C. S.
Daniel
,
P. B.
Prangnell
,
S.
Michalik
,
O. V.
Magdysyuk
,
T.
Connolley
,
M.
Drakopoulos
Diamond Proposal Number(s):
[13828]
Open Access
Abstract: An improved understanding of the phenomenon of dynamic precipitation is important to accurately model and simulate many industrial manufacturing processes with high strength Al-alloys. Dynamic ageing in 7xxx Al-alloys can occur as a result of both the strain and heat. Small angle X-ray scattering (SAXS) is an advanced technique that allows the precipitation processes to be studied in situ, but to date this has only been possible at lower than industrially relevant strain rates (e.g. < 10−3). In this contribution, we demonstrate the potential of in-situ SAXS studies of metallic alloys at higher strain rates (10−2) than previously, using a high energy synchrotron X-ray. The time resolved SAXS information has been used to evaluate dynamic precipitate evolution models and has demonstrated that at high strain rates a new regime must be considered which includes the more significant effect of vacancy annihilation, leading to a clear strain rate, rather than just strain, kinetic dependence.
|
Dec 2020
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[22178]
Abstract: Fluid release from dehydration reactions is considered to have significant effects on the strength and dynamics of tectonic faults at convergent plate boundaries. It is classically assumed that the production of fluid leads to increased pore fluid pressures that perturb a fault's stress state and thereby facilitates and enhances deformation. This important assumption has never been supported by direct microstructural observations. Here, we investigate the role of gypsum dehydration in the deformation of evaporitic rocks using synchrotron-based time-resolved X-ray computed microtomography (4D) imaging. This approach enables the documentation of coupled chemical, hydraulic and mechanical processes on the grain scale. In our experiments with deforming halite-gypsum-halite sandwiches we observe that the fluid released by dehydrating gypsum accumulates at the gypsum-halite interface before a distributed hydraulic failure of the halite layer drains the fluid. From our observations we conclude that perceivedly impermeable halite layers in evaporites are unlikely to trap overpressured fluid, e.g., in thin-skinned tectonic detachment horizons. Moreover, as the hydraulic failure is diffuse and not localized, our experiments suggest that dehydration reactions alone may not explain intermediate depth seismicity in subduction zones. Our data demonstrate the significant potential that in-situ 4D imaging has for the grain-scale investigation of fundamental tectonic processes.
|
Dec 2020
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
Yunhui
Chen
,
Samuel J.
Clark
,
Yuze
Huang
,
Lorna
Sinclair
,
Chu Lun Alex
Leung
,
Sebastian
Marussi
,
Thomas
Connolley
,
Oxana V.
Magdysyuk
,
Robert C.
Atwood
,
Gavin J.
Baxter
,
Martyn A.
Jones
,
Iain
Todd
,
Peter D.
Lee
Diamond Proposal Number(s):
[20096]
Open Access
Abstract: The Directed Energy Deposition Additive Manufacturing (DED-AM) of SS316L was studied using in situ and operando synchrotron X-ray imaging to quantitively understand the effect of processing parameters on the melt-pool morphology and surface quality. It was found that surface roughness of DED-AM builds can result from melt pool surface perturbations caused by changes in the melt flow and build stage motion perturbations. Process maps are developed that quantitatively correlate build quality to process parameters including powder feed rate, laser power and traverse speed. How the AM process parameters control build efficacy is clarified, and the processing conditions required to dampen surface perturbations leading to roughness were determined.
|
Dec 2020
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
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.
|
Nov 2020
|
|