A5069577970- Additive Manufacturing Materials and Processes
- Additive Manufacturing and 3D Printing Technologies
- High Entropy Alloys Studies
- Advanced X-ray Imaging Techniques
- Laser Material Processing Techniques
- Welding Techniques and Residual Stresses
- Medical Imaging Techniques and Applications
- Laser-induced spectroscopy and plasma
- Advanced X-ray and CT Imaging
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear Materials and Properties
- Energetic Materials and Combustion
- Nuclear Physics and Applications
- High-Temperature Coating Behaviors
- High-pressure geophysics and materials
- High Temperature Alloys and Creep
- Spine and Intervertebral Disc Pathology
- Geological and Geochemical Analysis
- Scoliosis diagnosis and treatment
- Integrated Circuits and Semiconductor Failure Analysis
- Rock Mechanics and Modeling
- Aluminum Alloy Microstructure Properties
- Advanced MRI Techniques and Applications
- Drilling and Well Engineering
- Particle Accelerators and Free-Electron Lasers
Research Complex at Harwell
2018-2025
University College London
2020-2025
Rutherford Appleton Laboratory
2018-2024
Science and Technology Facilities Council
2018-2022
University of Manchester
2018-2020
Henry Royce Institute
2018
Abstract The laser–matter interaction and solidification phenomena associated with laser additive manufacturing (LAM) remain unclear, slowing its process development optimisation. Here, through in situ operando high-speed synchrotron X-ray imaging, we reveal the underlying physical during deposition of first second layer melt tracks. We show that laser-induced gas/vapour jet promotes formation tracks denuded zones via spattering (at a velocity 1 m s −1 ). also uncover mechanisms pore...
Abstract Keyhole porosity is a key concern in laser powder-bed fusion (LPBF), potentially impacting component fatigue life. However, some keyhole formation mechanisms, e.g., fluctuation, collapse and bubble growth shrinkage, remain unclear. Using synchrotron X-ray imaging we reveal behaviour, quantifying their dynamics. The findings support the hypotheses that: (i) can initiate not only unstable, but also transition regimes created by high power-velocity conditions, causing fast radial...
Abstract Imaging intact human organs from the organ to cellular scale in three dimensions is a goal of biomedical imaging. To meet this challenge, we developed hierarchical phase-contrast tomography (HiP-CT), an X-ray phase propagation technique using European Synchrotron Radiation Facility (ESRF)’s Extremely Brilliant Source (EBS). The spatial coherence ESRF-EBS combined with our beamline equipment, sample preparation and scanning developments enabled us perform non-destructive,...
Abstract Porosity in directed energy deposition (DED) deteriorates mechanical performances of components, limiting safety-critical applications. However, how pores arise and evolve DED remains unclear. Here, we reveal pore evolution mechanisms during using situ X-ray imaging multi-physics modelling. We quantify five contributing to formation, migration, pushing, growth, removal entrapment: (i) bubbles from gas atomised powder enter the melt pool, then migrate circularly or laterally; (ii)...
Keyhole instability during laser welding and powder bed fusion (LPBF) can cause keyhole collapse pore formation. Using high-speed x-ray imaging, we demonstrate that the flow vortex-induced protrusion on rear wall is crucial in initiating instability. Applying a transverse magnetic field suppresses by driving secondary thermoelectric magnetohydrodynamics (TEMHD) alters net vortex. This minimizes protrusions large-amplitude oscillations. The suppression effectiveness depends scanning direction...
Laser-matter interactions in laser additive manufacturing (LAM) occur on short time scales (10−6–10−3 s) and have traditionally proven difficult to characterise. We investigate these during LAM of stainless steel SS316L 13-93 bioactive glass powders using a custom built process replicator (LAMPR) with situ operando synchrotron X-ray real-time radiography. This reveals wide range melt track solidification phenomena as well spatter porosity formation. hypothesise that the powder absorbs energy...
Laser powder bed fusion (LPBF) additive manufacturing of 2XXX series Al alloys could be used for low volume specialist aerospace components, however, such exhibit hot cracking susceptibility that can lead to component failure. In this study, we show two approaches suppress the formation cracks by controlling solidification behaviour using: (1) TiB2 additions; and (2) optimisation LPBF process parameters. Using high-speed synchrotron X-ray radiography, monitored Al-2139 in situ, with without...
Surface roughness controls the mechanical performance and durability (e.g., wear corrosion resistance) of laser powder bed fusion (LPBF) components. The evolution mechanisms surface during LPBF are not well understood due to a lack in situ characterisation methods. Here, we quantified key processes defect dynamics using synchrotron X-ray imaging ex optical explained side-skin top-skin multi-layer Ti-6AI-4V (where down-skin was out project scope). We found that average alone is an accurate...
Abstract Keyhole porosity is a key concern in laser powder-bed fusion (LPBF), potentially impacting component fatigue life. However, the dynamics of keyhole formation, i.e., fluctuation, collapse and bubble growth shrinkage, remain unclear. Using synchrotron X-ray imaging we reveal behaviours, quantifying their formation mechanisms. The findings support hypotheses that: (i) can initiate not only unstable, but also transition regimes, created by high power-velocity conditions, causing fast...
Abstract Laser powder bed fusion (LPBF) can produce high‐value metallic components for many industries; however, its adoption safety‐critical applications is hampered by the presence of imperfections. The interdependency between imperfections and processing parameters remains unclear. Here, evolution porosity humps during LPBF using X‐ray electron imaging, a high‐fidelity multiphase process simulation, quantified. pore keyhole formation mechanisms are driven mixing high temperatures metal...
Melt flow is critical to build quality during additive manufacturing (AM). When an external magnetic field applied, it causes forces that alter the through thermoelectric magnetohydrodynamic (TEMHD) effect, potentially altering final microstructure. However, extent of TEMHD and their underlying mechanisms, remain unclear. We trace tungsten particles using in situ high-speed synchrotron X-ray radiography ex tomography reveal structure TEMHD-induced directed energy deposition AM (DED-AM). no...
During directed energy deposition (DED) additive manufacturing, powder agglomeration and sintering can occur outside of the melt pool when using titanium alloy powders. Using in situ synchrotron radiography we investigate mechanisms by which Ti6242 occurs around pool, performing a parametric study to determine influence laser power stage traverse speed on sinter build-up. The results reveal that detrimental be reduced high or increased speed, although latter also reduces layer thickness....
Abstract Technological advancements in X-ray imaging using bright and coherent synchrotron sources now allows the decoupling of sample size resolution while maintaining high sensitivity to microstructures soft, partially dehydrated tissues. The continuous developments multiscale resulted hierarchical phase-contrast tomography, a comprehensive approach address challenge organ-scale (up tens centimeters) soft tissue with down cellular level. Using this technique, we imaged ex vivo an entire...
Directed energy deposition (DED) is a promising additive manufacturing technique for repair; however, DED prone to surface waviness (humping) in thin-walled sections, which increases residual stresses and crack susceptibility, lowers fatigue performance. Currently, the formation mechanism not well understood due lack of operando monitoring methods with high spatiotemporal resolution. Here, we use inline coherent imaging (ICI) optically monitor topology detect cracking situ, coupled...
Abstract Marangoni flow has a substantial influence on the quality of components fabricated via laser powder bed fusion (LPBF). However, in melt pools is rarely quantified due to opacity liquid metals and necessity for situ evaluation. Here we report findings high-temporal-resolution synchrotron x-ray radiography experiments tracking melt-pool. Dense, highly attenuating tungsten carbide particles are seeded within an elemental blend aluminium copper varying composition. Due extremely high...
Blended Elemental powders are an emerging alternative to pre-alloyed in metal additive manufacturing due the wider range of alloys producible with them and cost savings from not developing novel feedstock. In this study, situ alloying concurrent microstructure evolution during SLM investigated by performing on a BE Ti-185 powder while tracking surface temperatures via Infra-red imaging phase transforma- tion synchrotron X-ray Diffraction. We then performed post-mortem electron microscopy...
Gas flow rates in Directed Energy Deposition (DED) Additive Manufacturing (AM) can significantly affect the quality of built parts by altering melt pool geometry. Using a DED process replicator and situ synchrotron radiography, together with analogous experiments an industrial machine, we investigate impact carrier gas shield on build quality. The results reveal that there is critical rate above which pools are flattened, tracks widen, thus layer thickness decreases. reduction most prominent...