In this study, a tungsten-copper (W-Cu) composite was successfully deposited on mild steel substrate using a novel technique-Plasma Transferred Arc (PTA) welding. Spherical W and Cu powders were employed, and the resulting microstructural characteristics on a mild steel substrate were thoroughly analysed. Key PTA process parameters were established and found to significantly influence microstructural evolution. Notably, iron (Fe) dilution from the base metal markedly altered the composite's microstructure, and grain boundary diffusion of Cu into the mild steel substrate was observed. The size and morphology of W powder were found to affect the homogeneity and porosity of the deposited layer. X-ray diffraction and EDS point analysis revealed the formation of a new intermetallic phase, Fe7W6, around W particles. For the first time, a new intermetallic phase FeW was also confirmed by point EDS analysis. The intermetallic phase Fe7W6 was further confirmed by transmission electron microscopy (TEM) diffraction, indicating its stability at room temperature. Higher hardness values of the intermetallic phase were compared to other phases present in the composite.

Wire Arc Additive Manufacturing (WAAM) of 316L stainless steel typically results in columnar grains, high dislocation densities, and residual porosity, which limit toughness compared to conventional material. This study evaluates Hot Isostatic Pressing (HIP) as a post-processing route to refine the microstructure and eliminate defects by investigating four HIP cycles (1000-1200 degrees C, 100-150 MPa) using EBSD-EDS, neutron diffraction, tomography, and mechanical testing. Increasing HIP temperature and pressure promoted dislocation recovery and recrystallisation while dissolving metastable delta-ferrite; however, processing at 1000 degrees C induced brittle sigma-phase formation, while the 1200 degrees C/150 MPa cycle (HIP-4) produced a fully recrystallised, chemically homogeneous austenitic structure. HIP-4 reduced porosity by 98.8 % and restored a mechanical response comparable to conventionally processed 316L, characterised by improved ductility and strain-hardening capacity despite a reduction in yield strength. Ultimately, HIP-4 establishes an optimal post-processing window for achieving concurrent densification and microstructural homogenisation, significantly enhancing the mechanical performance and reliability of WAAM 316L components.

Lower-carbon concretes have cement-based binders partially substituted with supplementary cementitious materials (SCMs), which reduce embodied carbon. However, this substitution also increases susceptibility to carbonation and potentially for carbonation-induced corrosion. The transport properties of the binder play a crucial role in understanding these risks. Understanding these properties is already complex in plain cement systems, and the challenge is further amplified when cement is partially replaced with SCMs. This study uses neutron radiography to investigate water transport properties in low-carbon cementitious materials by capillary action. The technique allows for visualization of the changes in the water content, enabling estimation of the water transport rate through cement paste and SCM-blended binders. The findings show marked differences in water transport rates between pastes and mortars with and without SCMs, as well as between carbonated and non-carbonated samples. Considering that corrosion propagation in carbonated concrete depends on its transport properties, these observations provide insights into the potential durability characteristics.

In recent years, W-Cu composite systems have become very interesting subjects due to good electrical and thermal conductivity, high-temperature strength, certain plasticity, and excellent radiation resistance. W-Cu composites are a very important class of materials in applications like PFM (plasma facing materials), functional graded materials (FGM), electronic packaging materials, high-voltage electrical contacts, sweating materials, shaped charge liners, electromagnetic gun-rail materials, kinetic energy penetrators, and radiation shielding/protection. There is no possibility of forming a crystalline structure between these two materials. However, due to the unique properties these materials possess, they can be used by preparing them as a composite. Generally, W-Cu composites are prepared via the conventional powder metallurgy routes, i.e., sintering, hot pressing, hot isostatic pressing, isostatic cold pressing, sintering and infiltration, and microwave sintering. However, these processes have certain limitations, like the inability to produce bulk material, they are expensive, and their adoptability is limited. Here, in this review, we will discuss in detail the fabrication routes of additive manufacturing, and its current progress, challenges, trends, and associated properties obtained. We will also explain the challenges for the additive manufacturing of the composite. We will also compare W-Cu composites to other materials that can challenge them in terms of specific applications or service conditions. The solidification mechanism will be explained for W-Cu composites in additive manufacturing. Finally, we will conclude the progress of additive manufacturing of W-Cu composites to date and suggest future recommendations based on the current challenges in additive manufacturing.

In this work, we extend our previously published Monte Carlo simulation model of the Dingo thermal neutron beamline at the Australian Centre for Neutron Scattering model by (1) including a sapphire crystal filter in the model, and (2) utilising the NCrystal package to simulate thermal neutron interactions with the crystalline structure. In addition to previous experimental measurements performed in the beamline’s high-resolution mode, the beam was experimentally characterised in its high-intensity mode upstream from the sample stage (at the tertiary shutter wall exit) and these measurements were used as inputs for the model. The planar neutron distributions were optimised at both the sample stage and tertiary shutter wall exit, and model predictions were validated against experimental gold wire activation measurements. For both configurations—with and without the sapphire filter—we measured neutron fluxes, and performed neutron activation analysis using 11 materials to improve the accuracy of the neutron spectrum in the model relative to the original version. Using the optimised spectrum, we simulated out-of-beam neutron spectra that were further used as the initial input in unfolding code to explore the capability of the current solution to accurately reproduce the experimental results. The normalised neutron planar distribution from the simulation was on average within 2% at the centre, and 6% and 24% at the penumbra of the experimental results at the tertiary shutter wall exit and sample stage, respectively. The specific activities predicted by the refined model were within an average of 13% and 5% of the experimentally measured activities with and without the sapphire filter, respectively. We observed a decrease of around 45% in thermal neutron flux when the sapphire filter is used, which has been reproduced by the model. The maximum value of the logarithm of the ratio of simulated to experimental out-of-beam neutron spectra across 8 locations was 0.6 compared to 2.0 in the previous work, resulting in an average normalised root mean squared error between the unfolded spectrum and experimental measurements of 5% and 9% with and without the filter, respectively. Without the sapphire filter, the optimised predicted in-beam neutron spectrum consists of around 59% thermal, 21% epithermal and 20% fast neutrons, while the addition of the filter provides an almost pure (approximately 98%) thermal neutron beam.

This study aims to fabricate tungsten-copper (W-Cu) composites-critical for high thermal and electrical applications-using a novel, high-speed, and cost-effective plasma transferred arc (PTA) welding technique, as an alternative to conventional powder metallurgy methods. W-Cu composites were successfully fabricated for the first time as additive beads and deposits on copper substrates using a direct current (DC) tungsten inert gas (TIG) torch in a plasma transferred arc (PTA) welding process. Compared to mild steel, utilizing a Cu baseplate and controlling the interpass temperature resulted in a more homogeneous composite with some distributed porosity. Microstructural observations indicated that W particles impeded the flow of copper into vacant pore areas. Surface melting of tungsten particles was observed, with some particles transforming into slender shapes causing internal porosities. Improved shielding during single additive bead deposition minimized porosity, whereas thicker additive layers led to copper oxidation, causing lack of fusion and oxide inclusions. Transmission electron microscopy (TEM) revealed a distinct boundary between W and CU, with no atomic intermixing across the interface. Overall, the fabrication of W-Cu composites using the plasma transferred arc (PTA) additive manufacturing route was successfully achieved for the first time.

We present a method to shape a neutron beam and project any specified target image using a single universal patterned mask that is transversely displaced. The method relies on “ghost projection”, which is a reversed form of classical ghost imaging. A set of sub-mask regions that combine to construct the required beam shape is computed; illumination of each region with the determined exposure time projects the shaped beam. We demonstrate this method experimentally, using the Dingo neutron imaging beamline at the OPAL nuclear research reactor (Australia). The ability to shape a neutron beam “on demand” allows selective dose delivery away from sensitive areas of samples, such as in cultural heritage artifacts. It also benefits irradiation techniques, e.g., in testing resilience of electronic components for space and defense technologies or neutron therapies.

This study explores the development of a novel composite coating system combining the high hardness of WC and thermal conductivity of Cu, employing the plasma transfer arc welding method under ambient conditions. Utilizing an advanced welding approach, the work investigates microstructural evolution and phase formation in a WC-Cu-based coating applied to a mild steel substrate. Emphasis is placed on understanding the solidification behaviour and its influence on defects, microstructural refinement, and carbide formation. The study provides insights into the interactions between coating constituents and the underlying substrate under controlled thermal conditions. These findings demonstrate the potential for producing functionally graded coatings tailored for demanding wear and heat dissipation applications. The approach offers a pathway for enhancing the durability and performance of steel components in extreme service environments.

In this study, a WC-Cu composite coating was successfully fabricated on a mild steel substrate using the novel Plasma Transferred Arc (PTA) welding technique. Phase identification was carried out using X-ray diffraction (XRD), while microstructural evolution was analysed through scanning electron microscopy (SEM). The results indicate that WC particles predominantly interacted with Fe from the substrate, leading to the formation of complex carbides, primarily of the M₁₂C type, within the solution matrix. In contrast, Cu was observed to segregate and remain in discrete regions near the top surface of the coating. The M₁₂C carbides precipitated in two distinct morphologies: coarse, faceted dendritic structures forming equiaxed branches, and herringbone-shaped eutectic structures distributed along the α-Fe grain boundaries. The formation and growth of the eutectic M₁₂C phase was strongly influenced by the thermal gradients and solidification dynamics associated with the PTA welding process. This study highlights the potential of PTA welding for producing wear-resistant composite coatings with tailored microstructures through controlled solidification behaviour.

Neutron Capture Therapy (NCT) for cancer treatment is experiencing renewed interest due to advancements in accelerator-based neutron beams, treatment planning software, and patient positioning devices. This study presents the adaptation of an existing neutron radiography beamline (Dingo), at the OPAL research nuclear reactor, for radiobiological research and novel neutron capture agent development. Human glioblastoma cell cultures were irradiated for up to 10 min with a flux of 2.57 × 10 8 n/cm 2 s (± 2.73 × 10 7 ) and the resulting impact was quantified by assessing DNA damage by both immunocytochemistry and flow cytometry. This low cost methodology extends the capability of an existing beamline to allow the development of novel neutron capture agents and study of neutron radiobiological mechanisms. Increasing availability of neutron sources for biological study in this fashion will accelerate the development of NCT for disease specific clinical application.

The microstructure and high-temperature creep mechanisms of Ni-based Hastelloy C276 superalloy fabricated using wire and arc-based directed energy deposition were investigated systematically and innovatively. The microstructural investigation revealed that the as-fabricated samples comprise γ-Ni matrix and topologically close-packed (TCP) P phase precipitates. The γ matrix subgrains and grains are spread over multiple highly textured columnar dendrites, with a majority of γ <001> crystallographic orientations closely aligned along the deposition direction. Moreover, the interdendritic regions exhibit severe Mo segregation, P phase particles, and dislocation bands. Creep tests were conducted on miniature samples under various temperature and stress conditions, loaded either in the deposition direction (DD) or travel direction (TD). DD samples exhibit lower minimum strain rates, greater strains-to-failure, and longer creep rupture lifetimes than TD samples, indicating significant creep anisotropy. Dislocation creep was identified as the primary creep mechanism for both DD and TD conditions. During creep, dynamic precipitation of TCP phases occurred in the interdendritic regions, resulting in varying creep resistance between interdendritic and dendritic core regions. Isostress and isostrain models, considering both crystallographic texture and precipitation strengthening, reasonably predicted the observed creep anisotropy during the secondary creep stage. Additionally, variations in the Schmid factor led to significant deformation incompatibility among dendrites in TD samples. Dislocation accumulation in TD sample interdendritic regions promoted new grain nucleation, triggering dynamic recrystallisation, facilitating grain boundary sliding, and accelerating tertiary creep. Furthermore, TCP phase particles in the interdendritic regions contributed to microcrack development, further accelerating creep fracture, especially in the TD condition.

This state-of-the-art review is geared toward elucidating the molecular understanding of the carbon-based flame-retardant mechanisms for polymers via holistic characterization combining detailed analytical assessments and computational material science. The use of carbon-based flame retardants, which include graphite, graphene, carbon nanotubes (CNTs), carbon dots (CDs), and fullerenes, in their pure and functionalized forms are initially reviewed to evaluate their flame retardancy performance and to determine their elevation of the flammability resistance on various types of polymers. The early transition metal carbides such as MXenes, regarded as next-generation carbon-based flame retardants, are discussed with respect to their superior flame retardancy and multifunctional applications. At the core of this review is the utilization of cutting-edge molecular dynamics (MD) simulations which sets a precedence of an alternative bottom-up approach to fill the knowledge gap through insights into the thermal resisting process of the carbon-based flame retardants, such as the formation of carbonaceous char and intermediate chemical reactions offered by the unique carbon bonding arrangements and microscopic in-situ architectures. Combining MD simulations with detailed experimental assessments and characterization, a more targeted development as well as a systematic material synthesis framework can be realized for the future development of advanced flame-retardant polymers.

This work presents an experimentally validated Monte Carlo simulation model of the Dingo thermal neutorn beamline at the Austrlian Centre for Neutron Scattering (ACNS). The model was constructed using CAD drawings of the entire beam transport system and its material composition. The neutron spectrum was refined using in-beam nuetron activation analysis and outof-beam Bonner sphere spectroscopy. A sapphire filter was implemented and evaluated against experimental results. The model achieved good agreement with experimental data, with simulated neutron beam profiles within 2.3% and 1.6% of gold wire measurements at the tertiary sutter and sample stage, respectively. The refined neutron spectrum consists of 63.5% thermal, 16.2% epithermal and 20.2% fast neutrons, while the beam filtered by the sapphire filter constitutes 981% thermal neutron, and a decreased the thermal neutron flux by approximately 45%. Out-of-beam neutron spectra and counts root mean square errors (RMSE) were within $5.0+/-1.4 \%$ and $9.1+/-0.5 \%$, respectively. The model’s accuracy and flexibility offer advantages to Dingo users and the neutronics community.

Purpose Neutron Capture Enhanced Particle Therapy (NCEPT) is a proposed augmentation of charged particle therapy which exploits thermal neutrons generated internally, within the treatment volume via nuclear fragmentation, to deliver a biochemically targeted radiation dose to cancer cells. This work is the first experimental demonstration of NCEPT, performed using both carbon and helium ion beams with two different targeted neutron capture agents (NCAs). Materials and Methods Human glioblastoma cells (T98G) were irradiated by carbon and helium ion beams in the presence of NCAs, [ 10 B]-BPA and [ 157 Gd]-DOTA-TPP. Cells were positioned within a PMMA phantom either laterally adjacent to, or within, a 100×100×60 mm spread out Bragg peak (SOBP). The impact of NCAs and location relative to the SOBP on the cells was measured by cell growth and survival assays in six independent experiments. Neutron fluence within the phantom was characterised by quantifying the neutron activation of gold foil. Results Cells placed inside the treatment volume reached 10% survival by 2 Gy of C or 2-3 Gy of He in the presence of NCAs compared to 5 Gy of C and 7 Gy of He with no NCA. Cells placed adjacent to the treatment volume showed a dose-dependent decrease in cell growth when treated with NCAs, reaching 10% survival by 6 Gy of C or He (to the treatment volume), compared to a no detectable effect on cells without NCA. The mean thermal neutron fluence at the centre of the SOBP was approximately 2.2×10 9 n/cm2/Gy(RBE) for the carbon beam and 5.8×10 9 n/cm2/Gy(RBE) for the helium beam and gradually decreased in all directions. Conclusions The addition of NCAs to cancer cells during C and He beam irradiation has a measurable impact on cell survival and growth in-vitro . Through the capture of internally generated neutrons, NCEPT introduces the concept of a biochemically targeted radiation dose to charged particle therapy. NCEPT enables the established pharmaceuticals and concepts of neutron capture therapy to be applied to a wider range of deeply situated and diffuse tumours, by targeting this dose to micro-infiltrates and cells outside of defined treatment regions. These results also demonstrate the potential for NCEPT to provide an increased dose to tumour tissue within the treatment volume, with a reduction in radiation doses to off target tissue.

This study evaluated the mechanical properties and self-healing performance of freshly casted and 19-month-aged bioconcrete samples with integrated sulfate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB) granules that were cultivated in an upflow anaerobic sludge blanket (UASB) reactor with synthetic wastewater. The 28-day compressive strength fulfilled the design requirement of 50 MPa. The apparent volume of permeable voids (AVPV) of fresh and aged bioconcrete met the limit of 13%. The self-healing ability was determined by exposing cracked bioconcrete to water media such as glucose, calcium acetate, tap water, and wastewater, which have shown calcite deposition in fresh and aged samples. The highest amount of calcite deposition was seen on fresh samples after glucose exposure (420 mu m) and on aged bioconcrete after calcium acetate exposure (320 mu m). Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS/XRD) results demonstrated that SRB/NRB granules survived mortar integration and deposition of calcite in both fresh and aged samples. The water permeability and acid resistance of bioconcrete samples were correlated to the amount of deposited calcite. (c) 2023 American Society of Civil Engineers.

Using waste-activated sludge as a source for non-axenic sulfate-reducing bacterial (SRB) granules, this study developed an innovative bioconcrete with 1% and 2% SRB granules. The mechanical properties (AS 1012.9 and AS 1012.21) and self-healing performance of bioconcrete was systematically examined. The 28-d compressive strength of bioconcrete samples met the design requirement of 50 MPa and the general limit of 13% for average volume of permeable voids (AVPV). Within 3-4 weeks, both 1% and 2% bioconcrete samples precipitated 300-400 mu m of calcite in different water media such as glucose, calcium acetate, tap water, and real wastewater. The SEM analysis revealed that SRB granules survived mortar incorporation and precipitated calcium carbonate in the form of calcite which were further confirmed by EDS and XRD analysis. The tap water healed 1% and 2% bioconcrete samples had water permeabilities 64.2% and 69.9% lower than the control, respectively. The mass loss in 5% sulfuric acid was 3.8% and 3.2% less, respectively, for 1% and 2% bioconcrete specimens with surface calcite deposition after 120 d.

Abstract In this study, we present a validated Geant4 Monte Carlo simulation model of the Dingo thermal neutron imaging beamline at the Australian Centre for Neutron Scattering. The model, constructed using CAD drawings of the entire beam transport path and shielding structures, is designed to precisely predict the in-beam neutron field at the position at the sample irradiation stage. The model’s performance was assessed by comparing simulation results to various experimental measurements, including planar thermal neutron distribution obtained in-beam using gold foil activation and $$^{10}$$ 10 B $$_{4}$$ 4 C-coated microdosimeters and the out-of-beam neutron spectra measured with Bonner spheres. The simulation results demonstrated that the predicted neutron fluence at the field’s centre is within 8.1% and 2.1% of the gold foil and $$^{10}$$ 10 B $$_{4}$$ 4 C-coated microdosimeter measurements, respectively. The logarithms of the ratios of average simulated to experimental fluences in the thermal (E $$_{th}<$$ th < 0.414 eV), epithermal (0.414 eV < E $$_{epi}<$$ epi < 11.7 keV) and fast (E $$_{fast}>$$ fast > 11.7 keV) spectral regions were approximately − 0.03 to + 0.1, − 0.2 to + 0.15, and − 0.4 to + 0.2, respectively. Furthermore, the predicted thermal, epithermal and fast neutron components in-beam at the sample stage position constituted approximately 18%, 64% and 18% of the total neutron fluence.

In this study, a Ni-based Hastelloy C276 alloy was prepared using cold metal transfer (CMT)-based directed energy deposition (DED) under different heat inputs with a zig-zag deposition path, integrated with active cooling and interlayer temperature control. Analogous mechanical properties were obtained for the fabricated alloys under different heat inputs (276, 368 and 553 J/mm) through effective interlayer temperature control. Such a broad processing window facilitates the large-scale industrial manufacturing and application of Hastelloy C276 by DED. Nevertheless, the lower heat input appears to slightly refine the microstructure and decrease the mechanical anisotropy of manufactured alloys, which is ascribed to combined effects of the manipulated bulk texture, refined dendrite arm spacing and reduced chemical segregation under lower heat input. Despite the variations of geometrically necessary dislocation (GND) densities with heat inputs, no significant change was observed in the average total dislocation density (TDD) in the microstructure of all samples as suggested by the peak profile analysis of Synchrotron X-ray diffraction data, which is advantageous for lowering the solidification cracking susceptibility. Moreover, all as-fabricated alloys present a typical strong fibre-type (200) crystallo-graphic bulk texture measured by neutron diffraction, while such texture was relatively weaker in the lowest heat input condition. This work provides a reliable approach for stable additive manufacturing of Hastelloy C276 alloy, and innovatively presents rationales of stabilised properties based on the obtained insights into micro-structure and bulk texture developments in a wide observation range by various techniques.

The aim of this chapter is to give an overview of basic and advanced state-of-the-art microstructural and spectroscopic analytics to investigate inorganic material corrosion in the context of biochemically aggressive sewers. The chapter covers optical methods, electron beam, X-ray and neutron techniques (SEM, MLA, XRF, XRD, CT, Neutron radiography and tomography), and spectroscopic methods (MAS-NMR, FT-IR, and Raman). For each technique, a short section on the fundamental scientific background of the method precedes and examples of data output from the latter in respect to the corrosion of cementitious materials including reinforced concrete is presented.