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

Instruments / Technical Area	Publication Details	Published
I12-JEEP: Joint Engineering, Environmental and Processing	Effects of melt pool flow on porosity levels in arc welding F. Wu , K. V. Falch , M. Drakopoulos , W. U. Mirihanage Iop Conference Series: Materials Science And Engineering 1274 6th International Conference on Advances in Solidification Processes (ICASP-6) DOI: 10.1088/1757-899X/1274/1/012011 Diamond Proposal Number(s): [20611] Open Access Show Abstract ▼ Abstract: Arc welding is one of the widely used approaches for joining metals. During the arc welding process, an electric arc creates intense heat to fuse metals that forms the melt pool between the parts to be welded together. Intensive flow fields are observable within the fusion weld pools as a result of multiple driving forces. The flow patterns within the melt pool significantly determine the shape of the weld joint and other attributes of the solidified joint, such as microstructure and defects. Porosity is one of the solidification-related defects that can bring a detrimental impact. During the formation and solidification of weld pools, gas bubbles that are formed can be driven in or out from the pool by the flow. In this work, employing in situ synchrotron X-rays, we have observed how different flow conditions and air-liquid interface are contributed to retaining and releasing the gas bubbles that formed during the arc welding. The results suggest that underpinning driving forces, such as electromagnetic forces, act on molten metal to retain the pores inside the weld joints; but, gravity-driven effects can contribute to reduce the porosity, with appropriate process conditions	Jan 2023
B16-Test Beamline I12-JEEP: Joint Engineering, Environmental and Processing	Practical implementations of speckle-based phase-retrieval methods in Python and GPU for tomography Nghia T. Vo , Hongchang Wang , Lingfei Hu , Tunhe Zhou , Marie-~christine Zdora , Hans Deyhle , Robert C. Atwood , Michael Drakopoulos SPIE Optical Engineering + Applications (2022) DOI: 10.1117/12.2636834 Diamond Proposal Number(s): [27987, 20763, 27144, 31131] Show Abstract ▼ Abstract: X-ray phase-contrast tomography (X-PCT) techniques are capable of imaging samples with small differences in densities. They enable scientists to study biological or medical samples using high energy X-rays, which means less X-ray absorption and less sample damage, with high contrast quality. One branch of these techniques known as speckle-based methods have been well developed and demonstrated on real applications by different groups of developers using their own codes. However, there is lack of collective effort to package these methods into an open-source software which is easy-to-install, easy-to-use, well-documented, and optimized for speed. Such software is crucial to make the X-PCT techniques accessible to generic users and become regular tools. This report demonstrates the effort which implements speckle-based phase-retrieval methods in Python and GPU.	Oct 2022
DIAD-Dual Imaging and Diffraction Beamline	DIAD: A new instrument for Dual Imaging and Diffraction at Diamond Light Source Sharif Ahmed , Hans Deyhle , Andrew James , James Le Houx , Peter Garland , Michael Drakopoulos , Christina Reinhard , Navid Aslani SPIE Optical Engineering + Applications 2022 DOI: 10.1117/12.2644677 Show Abstract ▼ Abstract: The DIAD beamline at Diamond Light Source is a new dual-beam instrument for quasi-simultaneous full-field imaging and powder diffraction. DIAD enables its users to visualise internal structures (in 2- and 3D) as well as identify and measure compositional and strain changes. The aim is to enable in-situ and in-operando experiments that require spatially correlated results from both X-ray Computed Tomography and X-ray Powder Diffraction. DIAD has two independent beams in the medium energy range (8-38keV) that are generated from a single source 10-pole wiggler. Both beams are combined at one sample position. Here, radiography and/or tomography can be performed using either a monochromatic or pink beam, with a 1.4 mm x 1.2mm field of view and a pixel size of 0.5 µm. Micro-diffraction is possible with a variable beam size between 13µm x 5 µm up to 50 µm x 50µm. The talk will start with a description of the multi-modal capabilities of DIAD and the unique data collection pipeline that has been developed to reduce post-processing workloads. This will be followed by recent results from the fields of material science and bioengineering. Finally, the talk will conclude by giving the audience tips on how to gain access to DIAD.	Oct 2022
DIAD-Dual Imaging and Diffraction Beamline	Flexible positioning of a large area detector using an industrial robot Christina Reinhard , Michael Drakopoulos , Christopher M. Charlesworth , Andrew James , Hiten Patel , Paul Tutthill , Davide Crivelli , Hans Deyhle , Sharif I. Ahmed Journal Of Synchrotron Radiation 29, 1004 - 1013 DOI: 10.1107/S1600577522006300 Diamond Proposal Number(s): [30995] Open Access Show Abstract ▼ Abstract: The DIAD beamline for Dual Imaging and Diffraction at Diamond Light Source has opted to use an industrial robot to position its Dectris Pilatus 2M CdTe diffraction detector. This setup was chosen to enable flexible positioning of the detector in a quarter-sphere around the sample position whilst reliably holding the large weight of 139 kg of detector, detector mount and cabling in a stable position. Metrology measurements showed that the detector can be positioned with a linear repeatability of <19.7 µm and a rotational repeatability of <16.3 µrad. The detector position stays stable for a 12 h period with <10.1 µm of movement for linear displacement and <3.8 µrad for rotational displacement. X-ray diffraction from calibration samples confirmed that the robot is sufficiently stable to resolve lattice d-spacings within the instrumental broadening given by detector position and beam divergence.	Jul 2022
I12-JEEP: Joint Engineering, Environmental and Processing	X-ray imaging of complex flow patterns during tungsten inert gas welding F. Wu , K. V. Falch , S. Ramachandran , M. Drakopoulos , W. U. Mirihanage Journal Of Materials Engineering And Performance 559 DOI: 10.1007/s11665-022-07042-6 Diamond Proposal Number(s): [20611] Open Access Show Abstract ▼ Abstract: Fusion welding techniques such as tungsten inert gas (TIG) welding process have been widely used in industrial and construction applications. The molten metal flow in the weld pool has a major impact on the microstructure evolution, chemical element distribution and defects formation during solidification, which subsequently determines the performance of the welds. However, limited real-time experimental data availability of internal flow behavior has been considered as a major barrier to achieve a thorough understanding and development of accurate weld pool prediction models. In situ x-ray imaging with the tracking particles facilitated us to visualize the flow evolution during the solid–liquid–solid transformation. Experimental results indicated the flow patterns are progressively becoming complicated with the expansion of the melt pool. The shape of the melt pool also changed according to this flow evolution. Our analysis of flow patterns concerning the underlying variation of the driving forces suggests that gravity-derived buoyancy has a considerable effect on determining fluid flow at the melt pool periphery compared to other regions.	Jun 2022
I12-JEEP: Joint Engineering, Environmental and Processing	Mapping flow evolution in gas tungsten arc weld pools Fan Wu , Thomas F. Flint , Ken Vidar Falch , Michael C. Smith , Michael Drakopoulos , Wajira Mirihanage International Journal Of Heat And Mass Transfer 179 DOI: 10.1016/j.ijheatmasstransfer.2021.121679 Diamond Proposal Number(s): [20611] Open Access Show Abstract ▼ Abstract: The complex flow within the molten metallic pool, during advanced manufacturing and joining processes such as welding and additive manufacturing, directly affects the performance of the final components; through the generation of various microstructures and strain gradients. Understanding of the flow within such melt pools can enhance the predictability of the final microstructures and therefore component performance. In situ synchrotron X-ray imaging is employed to observe and map the evolving flow patterns within gas tungsten arc weld pools using tracking particles. The experimentally observed flow patterns are compared with numerical simulations to gain additional insights on accurate predictability in relevance to the physical driving forces within the flow. The spatio-temporal distribution of the flow using the mapped data is analyzed by considering the evolution of driving forces acting throughout the weld pool. The results demonstrate quantitative benchmark flow mapping with confirmation of the overall mechanisms of weld pool flow.	Nov 2021
DIAD-Dual Imaging and Diffraction Beamline	Beamline K11 DIAD: a new instrument for dual imaging and diffraction at Diamond Light Source Christina Reinhard , Michael Drakopoulos , Sharif I. Ahmed , Hans Deyhle , Andrew James , Christopher M. Charlesworth , Martin Burt , John Sutter , Steven Alexander , Peter Garland , Thomas Yates , Russell Marshall , Ben Kemp , Edmund Warrick , Armando Pueyos , Ben Bradnick , Maurizio Nagni , A. Douglas Winter , Jacob Filik , Mark Basham , Nicola Wadeson , Oliver N. F. King , Navid Aslani , Andrew J. Dent Journal Of Synchrotron Radiation 28 DOI: 10.1107/S1600577521009875 Open Access Show Abstract ▼ Abstract: The Dual Imaging and Diffraction (DIAD) beamline at Diamond Light Source is a new dual-beam instrument for full-field imaging/tomography and powder diffraction. This instrument provides the user community with the capability to dynamically image 2D and 3D complex structures and perform phase identification and/or strain mapping using micro-diffraction. The aim is to enable in situ and in operando experiments that require spatially correlated results from both techniques, by providing measurements from the same specimen location quasi-simultaneously. Using an unusual optical layout, DIAD has two independent beams originating from one source that operate in the medium energy range (7–38 keV) and are combined at one sample position. Here, either radiography or tomography can be performed using monochromatic or pink beam, with a 1.4 mm × 1.2 mm field of view and a feature resolution of 1.2 µm. Micro-diffraction is possible with a variable beam size between 13 µm × 4 µm and 50 µm × 50 µm. One key functionality of the beamline is image-guided diffraction, a setup in which the micro-diffraction beam can be scanned over the complete area of the imaging field-of-view. This moving beam setup enables the collection of location-specific information about the phase composition and/or strains at any given position within the image/tomography field of view. The dual beam design allows fast switching between imaging and diffraction mode without the need of complicated and time-consuming mode switches. Real-time selection of areas of interest for diffraction measurements as well as the simultaneous collection of both imaging and diffraction data of (irreversible) in situ and in operando experiments are possible.	Nov 2021
I12-JEEP: Joint Engineering, Environmental and Processing	Data processing methods and data acquisition for samples larger than the field of view in parallel-beam tomography Nghia T. Vo , Robert C. Atwood , Michael Drakopoulos , Thomas Connolley Optics Express 29 DOI: 10.1364/OE.418448 Diamond Proposal Number(s): [22109, 24740, 14033, 19526, 21999] Open Access Show Abstract ▼ Abstract: Parallel-beam tomography systems at synchrotron facilities have limited field of view (FOV) determined by the available beam size and detector system coverage. Scanning the full size of samples bigger than the FOV requires various data acquisition schemes such as grid scan, 360-degree scan with offset center-of-rotation (COR), helical scan, or combinations of these schemes. Though straightforward to implement, these scanning techniques have not often been used due to the lack of software and methods to process such types of data in an easy and automated fashion. The ease of use and automation is critical at synchrotron facilities where using visual inspection in data processing steps such as image stitching, COR determination, or helical data conversion is impractical due to the large size of datasets. Here, we provide methods and their implementations in a Python package, named Algotom, for not only processing such data types but also with the highest quality possible. The efficiency and ease of use of these tools can help to extend applications of parallel-beam tomography systems.	May 2021
I12-JEEP: Joint Engineering, Environmental and Processing	Direct observation of the dynamic evolution of precipitates in aluminium alloy 7021 at high strain rates via high energy synchrotron X-rays 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 Acta Materialia DOI: 10.1016/j.actamat.2020.116532 Diamond Proposal Number(s): [13828] Open Access Show Abstract ▼ 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	Short range order and crystallization of Cu–Hf metallic glasses Stefan Michalik , Pál Jóvári , Karel Saksl , Martin Durisin , Dušan Balga , Jacques Darpentigny , Michael Drakopoulos Journal Of Alloys And Compounds DOI: 10.1016/j.jallcom.2020.156775 Diamond Proposal Number(s): [14465, 16332] Show Abstract ▼ Abstract: Detailed information on the atomic arrangement of glassy Cu54Hf46, Cu61Hf39 and Cu69Hf31 alloys has been obtained by the reverse Monte Carlo (RMC) simulation using high-energy X-ray diffraction and neutron diffraction data as input. Dominant cluster units are identified by means of the radical Voronoï tessellation technique. Cu-centred clusters show a stronger ordering level than the Hf-centred ones. Results are compared with those previously reported for analogous binary amorphous systems such as Zr–Cu and Zr–Ni. Additionally, the thermal stability of the studied Cu–Hf alloys has been inspected by in-situ high-temperature X-ray diffraction and differential scanning calorimetry measurements. A different structural evolution is observed for Cu69Hf31 compared with Cu54Hf46 and Cu61Hf39. Products of devitrification are identified and quantified. The better glass forming ability of Cu54Hf46 and Cu61Hf39 compared with Cu69Hf31 is explained in the view of short range order differences of glassy states and corresponding crystalline phases formed during devitrification.	Aug 2020

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