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

Instruments / Technical Area	Publication Details	Published
	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
I13-2-Diamond Manchester Imaging	Exploiting confinement to study the crystallization pathway of calcium sulfate Clara Anduix-Canto , Mark A. Levenstein , Yi-Yeoun Kim , Jose R. A. Godinho , Alexander N. Kulak , Carlos Gonzalez Nino , Philip J. Withers , Jonathan P. Wright , Nikil Kapur , Hugo K. Christenson , Fiona C. Meldrum Advanced Functional Materials DOI: 10.1002/adfm.202107312 Diamond Proposal Number(s): [13578, 17314] Open Access Show Abstract ▼ Abstract: Characterizing the pathways by which crystals form remains a significant challenge, particularly when multiple pathways operate simultaneously. Here, an imaging-based strategy is introduced that exploits confinement effects to track the evolution of a population of crystals in 3D and to characterize crystallization pathways. Focusing on calcium sulfate formation in aqueous solution at room temperature, precipitation is carried out within nanoporous media, which ensures that the crystals are fixed in position and develop slowly. The evolution of their size, shape, and polymorph can then be tracked in situ using synchrotron X-ray computed tomography and diffraction computed tomography without isolating and potentially altering the crystals. The study shows that bassanite (CaSO4 0.5H2O) forms via an amorphous precursor phase and that it exhibits long-term stability in these nanoscale pores. Further, the thermodynamically stable phase gypsum (CaSO4 2H2O) can precipitate by different pathways according to the local physical environment. Insight into crystallization in nanoconfinement is also gained, and the crystals are seen to grow throughout the nanoporous network without causing structural damage. This work therefore offers a novel strategy for studying crystallization pathways and demonstrates the significant impact of confinement on calcium sulfate precipitation, which is relevant to its formation in many real-world environments.	Sep 2021
I12-JEEP: Joint Engineering, Environmental and Processing	Damage accumulation during high temperature fatigue of Ti/SiCf metal matrix composites under different stress amplitudes Ying Wang , Xu Xu , Wenxia Zhao , Nan Li , Samuel A. Mcdonald , Yuan Chai , Michael D. Atkinson , Katherine J. Dobson , Stefan Michalik , Yingwei Fan , Philip J. Withers , Xiaorong Zhou , Timothy L. Burnett Acta Materialia 16 DOI: 10.1016/j.actamat.2021.116976 Diamond Proposal Number(s): [20226] Open Access Show Abstract ▼ Abstract: The damage mechanisms and load redistribution taking place under high temperature (350°C), high cycle fatigue (HCF) of TC17 titanium alloy/unidirectional SiC fibre composites have been investigated in situ using synchrotron X-ray computed tomography (CT) and X-ray diffraction (XRD) under two stress amplitudes. The three-dimensional morphology of the fatigue crack and fibre fractures has been mapped by CT. At low stress amplitude, stable growth occurs with matrix cracking deflecting by 50-100 µm in height as it bypasses the bridging fibres. At higher stress amplitude, loading to the peak stress led to a burst of fibre fractures giving rise to rapid crack growth. Many of the fibre fractures occurred 50-300 µm above/below the matrix crack plane during rapid growth, contrary to that in the stable growth stage, leading to extensive fibre pull-out on the fracture surface. The changes in fibre loading, interfacial stress, and the extent of fibre-matrix debonding in the vicinity of the crack have been mapped over the fatigue cycle and after the rapid growth by XRD. The fibre/matrix interfacial sliding extends up to 600 µm (in the stable-growth zone) or 700 µm (in the rapid-growth zone) either side of the crack plane. The direction of interfacial shear stress reverses over the loading cycle, with the maximum frictional sliding stress reaching ∼55 MPa in both regimes. In accordance with previous studies, it is possible that a degradation in fibre strength at elevated temperature is responsible for bursts of fibre fracture and rapid crack growth under higher stress amplitude.	May 2021
I13-2-Diamond Manchester Imaging	Following the effect of braid architecture on performance and damage of carbon fibre/epoxy composite tubes during torsional straining Yuan Chai , Ying Wang , Zeshan Yousaf , Malte Storm , Nghia T. Vo , Kaz Wanelik , Timothy L. Burnett , Prasad Potluri , Philip J. Withers Composites Science And Technology DOI: 10.1016/j.compscitech.2020.108451 Diamond Proposal Number(s): [13704, 18197] Open Access Show Abstract ▼ Abstract: The torsional performance of bi-axially braided carbon fibre reinforced polymer (CFRP) tubes as a function of braid architecture is investigated. It is found that for a given braid pattern, the 45° braided CFRP tubes have higher shear moduli and lower shear strength than the 35° braids. In general, 2/2 (regular) braided CFRP tubes exhibit both higher shear strength and higher shear modulus than 1/1 (diamond) braids. However, beyond the peak load, the shear strength of 2/2 braided CFRPs exhibits sudden, steep drops, resulting in a lower remnant shear strength than 1/1 structures after the shear strain exceeds 4.5%. Moreover, the damage evolution is monitored in-situ by synchrotron X-ray computed tomography during torsional straining. It showed that for a 2/2 structure, inter-tow debonded regions are vertically interconnected allowing rapid crack propagation and strength drops, whereas for the 1/1 braid they are distributed in a chequer board causing more gradual loss of strength. The fibre/matrix interfacial strength and tow cross-over density play key roles in the torsional failure of 1/1 and 2/2 braided CFRP tubes, as the former controls damage initiation and the latter controls damage propagation.	Sep 2020
I13-2-Diamond Manchester Imaging	Environmentally induced crack (EIC) initiation, propagation, and failure: A 3D in-situ time-lapse study of AA5083 H131 Visweswara Chakravarthy Gudla , Malte Storm , Benjamin C. Palmer , John J. Lewandowski , Philip J. Withers , N. J. Henry Holroyd , Timothy L. Burnett Corrosion Science DOI: 10.1016/j.corsci.2020.108834 Diamond Proposal Number(s): [18165] Show Abstract ▼ Abstract: Environment Induced Cracking (EIC) has been observed in three dimensions (3D) at high spatial and temporal resolution for AA5083 H131 alloy using in situ synchrotron X-ray CT. The initiation of EIC cracks occurred in humid air at ∼0.5σy and started from corrosion sites associated with intermetallic particle clusters. Time-resolved monitoring of the crack growth confirmed cracks grow below threshold KIEIC and are susceptible to arrest under fixed displacement conditions. Even when the cracks exceed threshold KIEIC and enter sustained propagation they exhibit very uneven growth rates. Failure occurs when the K of the largest crack exceeds the fracture toughness KIC.	Jun 2020
I13-2-Diamond Manchester Imaging	Multiscale image-based modelling of damage and fracture in carbon fibre reinforced polymer composites R. M. Sencu , Z. Yang , Y. C. Wang , P. J. Withers , C. Soutis Composites Science And Technology DOI: 10.1016/j.compscitech.2020.108243 Diamond Proposal Number(s): [10456] Show Abstract ▼ Abstract: This paper is the first to predict and then validate the overall stress-strain curve and the damage sequence comprising matrix cracking, interface debonding and fibre fracture against X-ray Computed Tomography (CT) observations for a multidirectional laminate. Until recently, numerical modelling of multi-directional multi-ply composites required idealised continuum mechanics models or idealised unit cell approaches (or homogenisation method) that cannot reliably capture property variations and the complex sequence of damage events that occur upon tensile loading. Here a multiscale image-based model is used to simulate stochastic crack growth in a double-notch (-45°/90°/+45°/0°/-45°/90°/+45°/0°)s carbon fibre reinforced polymer (CFRP) composite specimen subjected to tensile loading monitored by time-lapse X-ray CT. The data integration approach involves: (1) parallel simulations of meso-scale elements (MeEs) for each ply for which the orientation of the individual fibres has been extracted from an X-ray CT image, (2) local hierarchical coupling of the MeEs into a macro-scale mechanical model of the test piece, and (3) the use of a random variation in material properties where microstructural details are not revealed by the X-ray CT characterisation method. Cohesive interface elements (CIEs) are used at both scales to predict the accumulation of interface damage and crack growth. The fibre-level modelling captures the detailed damage sequence and crack morphology including fibre/matrix debonding, sliding, matrix cracking and fibre fracture events. The multiscale model is validated by comparison with the measured tensile loading curve and the damage evolution recorded by the X-ray CT.	May 2020
I12-JEEP: Joint Engineering, Environmental and Processing	The effect of grain size on the fatigue overload behaviour of nickel Wen Zhang , Christopher A. Simpson , Pablo Lopez-Crespo , Mehdi Mokhtarishirazabad , Thomas Buslaps , Reinhard Pippan , Philip J. Withers Materials & Design 189 DOI: 10.1016/j.matdes.2020.108526 Diamond Proposal Number(s): [16647] Open Access Show Abstract ▼ Abstract: The fatigue overload behaviours of coarse grain (~30 μm), ultrafine grain (360 nm) and nanocrystalline (~30 nm) Ni are compared under constant amplitude loading at R = 0.1 after a 100% overload. Synchrotron X-ray diffraction is applied to map the elastic crack-tip strain fields at the mid-thickness of a compact tension specimen of nanocrystalline Ni at various stages through the loading cycles, from which the variation in stress before, during and after overload is estimated. Digital image correlation is used to measure the crack length and the displacement fields at the specimen surfaces for both grain sizes, from which the fatigue crack growth (FCG) rate, crack opening displacement and stress intensity factor range are determined. The FCG for coarse grain Ni is most significantly retarded whereas the nanocrystalline Ni is least affected by the overload due to an increased yield stress and a more planar crack surface morphology. As a result, FCG retardation by plasticity, surface roughness and residual stress-induced crack closure are reduced.	Apr 2020
I13-2-Diamond Manchester Imaging	Damage evolution in braided composite tubes under torsion studied by in-situ X-ray computed tomography Yuan Chai , Ying Wang , Zeshan Yousaf , Nghia T. Vo , Tristan Lowe , Prasad Potluri , Philip J. Withers Composites Science And Technology DOI: 10.1016/j.compscitech.2019.107976 Diamond Proposal Number(s): [13704, 18197] Show Abstract ▼ Abstract: Here we present the first real-time three dimension (3D) observations of damage evolution in a composite tube under torsion. An in-situ torsion test of 1/1 45° (diamond) braided carbon fibre-epoxy circular composite tube was performed on a loading rig and the damage process was characterised by synchrotron X-ray computed tomography (CT). A number of damage modes and their damage sequence has been identified and monitored globally and in more detail within a representative region of interest. In particular, intra-tow cracks and inter-tow debonding have been found to occur almost simultaneously at low shear strains (1.5%). It is noteworthy that inter-tow debonding was initially trapped/limited within repeated braid units before propagating and connecting with other damage modes in 3D. The area fraction of inter-tow debonds was quantified at different stages and it was found to dramatically increase with increasing shear strain beyond 1.5%. The total volume fraction of the observed intra-tow cracks of various forms was seen to grow rapidly beyond shear strain of 2.0%. Beyond the peak shear stress (at shear strain of 2.5%), fibre micro-buckling and kink bands occur in the tows subjected to torsion induced axial compression at crimped regions close to tow crossovers. Tow crossovers control many aspects of damage propagation under torsion, positively by localising inter-tow debonds and negatively by initiating fibre micro-buckling.	Dec 2019
I12-JEEP: Joint Engineering, Environmental and Processing	The effect of anisotropic microstructure on the crack growth and fatigue overload behaviour of ultrafine-grained nickel W. Zhang , C. A. Simpson , T. Leitner , X. Zhang , R. Pippan , P. J. Withers Acta Materialia DOI: 10.1016/j.actamat.2019.11.024 Diamond Proposal Number(s): [16647] Show Abstract ▼ Abstract: Changes in crack growth rate associated with overload events during fatigue are poorly understood, especially for materials with anisotropic microstructures. Here overload fatigue tests are reported for compact tension samples cut in two different orientations from high pressure torsion disc samples. During growth the crack planes reoriented either slightly, or significantly, to align with the elongated grain structure leading to low, and high, levels of mixed mode fatigue loading respectively. In both cases the ultrafine grained microstructure led to macroscopically flat crack faces. The fatigue crack growth rate was around 3.4 times slower for the case with the high mode II component than for the low. A 100% overload was then introduced and synchrotron X-ray diffraction and digital image correlation (DIC) were applied in-situ to map the bulk crack-tip elastic strain field (plane strain) and surface displacement field (plane stress) respectively prior to, during and after overload. The high mode II case displayed a larger degree of retardation after overload. Residual stress and plasticity-induced crack closure were found to be the primary causes for the retardation as the crack grows into the overload plastic zone. Significant crack face contact was observed for the high mode II case along with significant levels of compressive stress transferred across the crack faces at minimum load. Compared with conventional (coarse) grain Ni, the ultrafine grained Ni is less retarded by overload, because of its relatively flatter crack path and higher yield stress and thus less plasticity and residual stress induced closure.	Nov 2019
I13-2-Diamond Manchester Imaging	Tracking capsule activation and crack healing in a microcapsule-based self-healing polymer S. A. Mcdonald , S. B. Coban , N. R. Sottos , P. J. Withers Scientific Reports 9 DOI: 10.1038/s41598-019-54242-7 Diamond Proposal Number(s): [4022] Open Access Show Abstract ▼ Abstract: Structural polymeric materials incorporating a microencapsulated liquid healing agent demonstrate the ability to autonomously heal cracks. Understanding how an advancing crack interacts with the microcapsules is critical to optimizing performance through tailoring the size, distribution and density of these capsules. For the first time, time-lapse synchrotron X-ray phase contrast computed tomography (CT) has been used to observe in three-dimensions (3D) the dynamic process of crack growth, microcapsule rupture and progressive release of solvent into a crack as it propagates and widens, providing unique insights into the activation and repair process. In this epoxy self-healing material, 150 µm diameter microcapsules within 400 µm of the crack plane are found to rupture and contribute to the healing process, their discharge quantified as a function of crack propagation and distance from the crack plane. Significantly, continued release of solvent takes place to repair the crack as it grows and progressively widens.	Nov 2019

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