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52 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	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
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
I12-JEEP: Joint Engineering, Environmental and Processing	In situ X-ray observations of transient states in arc weld pools F. Wu , K. V. Falch , M. Drakopoulos , W. U. Mirihanage Iop Conference Series: Materials Science And Engineering 861 MCWASP XV 2020 DOI: 10.1088/1757-899X/861/1/012071 Diamond Proposal Number(s): [20611] Open Access Show Abstract ▼ Abstract: Metallic alloys coalesce via extremely rapid melting and subsequent solidification to form fusion welded joints. The melt pool evolution in melting and solidification sequences during the welding process determines the formation of the final weld joint shape, microstructure and defects. The scientific insight on weld pool evolution and related phenomena can be a key contribution to enhance structural integrity and resilience of the welded structures or components. However, inherent complexity with multi-physics phenomena, associated high temperatures and the rapidness of the processes make direct experimental investigation of welding is extremely demanding. Thus, internal flow behaviour during welding or other melt-pool-based metal processing such as additive manufacturing remains unclear and hinders progression to process optimisation. In this contribution we report the observation of melt pool dynamics that take place during electric arc welding, obtained through in situ synchrotron imaging at millisecond scale. The analysis flow patterns along with the quantified weld pool surface dynamics revealed us to how different contributing forces dictate the flow conditions over the distinct durations of the relatively short existence of the liquid phase. Our preliminary results suggest the existence of arc, surface tension and gravity dominant regimes during the evaluation of the weld pool. Further, we present our observations on how different welding parameters influence these regimes and develop into different transient conditions.	May 2020
B16-Test Beamline I12-JEEP: Joint Engineering, Environmental and Processing	Time evolved force domination in arc weld pools Fan Wu , Ken Vidar Falch , Da Guo , Paul English , Michael Drakopoulos , Wajira Mirihanage Materials & Design DOI: 10.1016/j.matdes.2020.108534 Diamond Proposal Number(s): [20611, 19595] Open Access Show Abstract ▼ Abstract: The flow within the melt pool during welding is a major factor that dictates the formation of the final fusion zone shape, solidification microstructure and defects. In this paper, we report the evolution sequence of the arc weld pool flow that observed via fast in-situ synchrotron X-ray imaging. Varying flow regimes attribute to the dominance of characteristic forces within the weld pool during rapid solid-liquid-solid phase transformation. Our analysis indicates the general sequence in the arc, surface tension and gravity driven force domination. Welding process parameters appear to influence significantly in determining the domination interval and the intensity of individual force. In some instances, arc and surface tension driven forces can prevent pores, which causes porosity in final welded structures, escaping from the melt pool. Preliminary relations between power input levels, diffract force domination regimes, flow patterns and pool surface changes in fusion welds are suggested by considering the behavior of multiple weld pools.	Feb 2020
B22-Multimode InfraRed imaging And Microspectroscopy I11-High Resolution Powder Diffraction I12-JEEP: Joint Engineering, Environmental and Processing	Analysis by synchrotron X-ray scattering of the kinetics of formation of an Fe-based metal-organic framework with high CO 2 adsorption Harry G. W. Godfrey , Lydia Briggs , Xue Han , William J. F. Trenholme , Christopher Morris , Mathew Savage , Louis Kimberley , Oxana Magdysyuk , Michael Drakopoulos , Claire A. Murray , Chiu C. Tang , Mark D. Frogley , Gianfelice Cinque , Sihai Yang , Martin Schroeder Apl Materials 7 DOI: 10.1063/1.5121644 Diamond Proposal Number(s): [11278] Open Access Show Abstract ▼ Abstract: Understanding the mechanism of assembly and function of metal-organic frameworks (MOFs) is important for the development of practical materials. Herein, we report a time-resolved diffraction analysis of the kinetics of formation of a robust MOF, MFM-300(Fe), which shows high adsorption capacity for CO2 (9.55 mmol g−1 at 293 K and 20 bar). Applying the Avrami-Erofe’ev and the two-step kinetic Finke-Watzky models to in situ high-energy synchrotron X-ray powder diffraction data obtained during the synthesis of MFM-300(Fe) enables determination of the overall activation energy of formation (50.9 kJ mol−1), the average energy of nucleation (56.7 kJ mol−1), and the average energy of autocatalytic growth (50.7 kJ mol−1). The synthesis of MFM-300(Fe) has been scaled up 1000-fold, enabling the successful breakthrough separations of the CO2/N2 mixture in a packed-bed with a selectivity for CO2/N2 of 21.6. This study gives an overall understanding for the intrinsic behaviors of this MOF system, and we have determined directly the binding domains and dynamics for adsorbed CO2 molecules within the pores of MFM-300(Fe).	Nov 2019
Data acquisition	P99: An optical beamline for offline technique development and systems integration for prototype beamline instrumentation A. D. Parsons , S. Ahmed , M. Basham , D. Bond , B. Bradnick , M. Burt , T. Cobb , N. Dougan , M. Drakopoulos , F. Ferner , J. Filik , C. Forrester , L. Hudson , P. Joyce , B. Kaulich , A. Kavva , J. Kelly , J. Mudd , B. Nutter , P. Quinn , K. Ralphs , C. Reinhard , J. Shannon , M. Taylor , T. Trafford , X. Tran , E. Warrick , A. Wilson , A. D. Winter ICALEPCS2019 DOI: 10.18429/JACoW-ICALEPCS2019-WEBPP04 Open Access Show Abstract ▼ Abstract: We present a beamline analogue, capable of system pro- totyping, integrated development and testing, specifically designed to provide a facility for full scientific testing of instrument prototypes. With an identical backend to real beamline instruments the P99 development rig has allowed increased confidence and troubleshooting ahead of final scientific commissioning. We present detail of the software and hardware components of this environment and how these have been used to develop functionality for the new operational instruments. We present several high impact examples of such integrated prototyping development in- cluding the instrumentation for DIAD (integrated Dual Im- aging And Diffraction) and the J08 (Soft X-ray ptychogra- phy) beamline end station.	Oct 2019
I12-JEEP: Joint Engineering, Environmental and Processing	Preprocessing techniques for removing artifacts in synchrotron-based tomographic images Nghia Vo , Robert C. Atwood , Michael Drakopoulos SPIE Optical Engineering + Applications, 2019 DOI: 10.1117/12.2530324 Open Access Show Abstract ▼ Abstract: X-Ray parallel-beam micro-tomography systems at synchrotron facilities are mainly bespoke designs. Technical problems from a detector system can strongly affect the quality of reconstruction results. Radial lens distortion in the visible light optics causes streak artifacts which get stronger towards the edge of the image. The irregular response of the detector gives rise to a variety of stripe artifacts in the sonogram; full stripes, partial stripes, fluctuating stripes, and unresponsive stripes. These give rise to ring artifacts of different kinds in the reconstructed image. The scattering of the scintillation photons can cause artifacts which are similar to beam hardening artifacts and reduce the resolution of the image. Here we present our practical approaches to tackle each such problem. These approaches are easy to implement and have low computational cost. The algorithms are freely available as open-source software.	Sep 2019
I12-JEEP: Joint Engineering, Environmental and Processing Optics	High-energy, high-resolution, fly-scan X-ray phase tomography Hongchang Wang , Robert C. Atwood , Matthew James Pankhurst , Yogesh Kashyap , Biao Cai , Tunhe Zhou , Peter David Lee , Michael Drakopoulos , Kawal Sawhney Scientific Reports 9, 8913 DOI: 10.1038/s41598-019-45561-w Diamond Proposal Number(s): [14033] Open Access Show Abstract ▼ Abstract: High energy X-ray phase contrast tomography is tremendously beneficial to the study of thick and dense materials with poor attenuation contrast. Recently, the X-ray speckle-based imaging technique has attracted widespread interest because multimodal contrast images can now be retrieved simultaneously using an inexpensive wavefront modulator and a less stringent experimental setup. However, it is time-consuming to perform high resolution phase tomography with the conventional step-scan mode because the accumulated time overhead severely limits the speed of data acquisition for each projection. Although phase information can be extracted from a single speckle image, the spatial resolution is deteriorated due to the use of a large correlation window to track the speckle displacement. Here we report a fast data acquisition strategy utilising a fly-scan mode for near field X-ray speckle-based phase tomography. Compared to the existing step-scan scheme, the data acquisition time can be significantly reduced by more than one order of magnitude without compromising spatial resolution. Furthermore, we have extended the proposed speckle-based fly-scan phase tomography into the previously challenging high X-ray energy region (120 keV). This development opens up opportunities for a wide range of applications where exposure time and radiation dose are critical.	Jun 2019

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