Magnesium and its alloys are increasingly used in automotive and aerospace industries due to their low density, which supports lightweighting and reduces environmental impact. However, their broader application is limited by poor formability, largely resulting from strong textures formed during mechanical processing that reduce ductility. Extensive research has focused on mitigating this issue through alloying and optimised processing. While rare earth (RE) elements are highly effective in weakening texture, their scarcity drives interest in alternative approaches. This review discusses the mechanisms by which RE elements influence texture, explores the potential of non-RE elements, particularly calcium, and highlights promising results from multi-component alloying. It also examines key processing parameters for the AZ31 alloy, emphasising properties, industrial feasibility, and directions for alloy development.

Laser Additive Manufacturing (LAM)-induced directional solidification creates complex microstructures in nickel-based superalloys, featuring columnar grains with cellular sub-grains and carbides. Using Scanning 3D X-ray Diffraction (S3DXRD), we reveal orientation and intergranular strain relationships coupled to cellular sub-grain networks and primary cubic MC carbides. We analyzed 3D orientation and elastic strain fields across 82 γ grains and 37,000+ carbides in an ABD-900AM alloy produced via Directed Energy Deposition (DED). Cooling-induced solute segregation creates volumetric lattice parameter patterning in the γ phase, altering residual stress fields. Ti-, Ta-, and Nb-rich carbides form preferentially in these high-solute regions, exhibiting weak orientation relationships with parent γ grains. These results provide the first non-destructive 3D study linking rapid solidification segregation, deformation heterogeneity, and carbide architectures in additively manufactured Ni-superalloys. These insights provide crucial detail to rationalise LAM process parameter optimisation and the coupled spatially governed structural performance. Researchers present a highly detailed, synchrotron resolved, 3D microstructural investigation of how tiny structures/defects form inside nickel superalloys during metal additive manufacturing, with the goal of helping engineers build tougher jet engines and turbine parts.

The brittleness of W at low temperatures remains a major challenge for its application in load-bearing components. To address this problem, two strategies were explored in this study: (1) the application of plastic deformation via rolling and (2) alloying with the ductilising element, Rhenium (Re). To study the combined effects of thermo-mechanical processing and alloying, sheets of W and W-25Re (wt.%) were prepared using powder metallurgy and rolling. Average grain sizes of 0.4 mu m and 0.6 mu m were measured perpendicular to the rolling direction, for the Wand W-25Re sheets respectively. Additionally, the W-25Re sheet was annealed at 1650 degrees C to form large, recrystallised grains that would typically be associated with brittle behaviour in unalloyed W. Characterisation of the as-rolled materials revealed highly textured microstructures with elongated grains with a preferential (110) orientation aligned parallel to the rolling direction. Tensile yield stresses of 1.82 GPa and 1.33 GPa were obtained for the rolled W and W-25Re respectively, while the recrystallised W-25Re had a yield stress of 0.99 GPa. The elongation to failure was significantly increased by Re alloying from 4 % up to 22 % at room temperature in the rolled material. Examination of the fracture surfaces revealed that the rolled materials failed via transgranular cleavage at room temperature, whereas the recrystallised W-25Re failed by intergranular fracture. There was also evidence of microcracking at room temperature for all three materials which suggested the initial stages of a transition to a delamination failure mode at elevated temperatures. An increase in necking was seen for W-25Re compared with W and an increase in plastic deformation because of alloying. Microcracking in the rolled W may accommodate some of the 4 % elongation measured despite the fact the material had a fracture surface typical of brittle failure. We demonstrate that Re alloying imparts an increase in ductility that can be utilised in combination with rolling to produce strong materials with high temperature compatibility and exceptional room temperature ductility.

For nickel-base superalloys fabricated from gas-atomised powders, the final microstructure must be related to the characteristics of the powder itself. This work provides detailed characterisation, primarily using transmission electron microscopy, to link microstructure, composition and crystallography of the nickel-base superalloy, RR1000. In the virgin state, the powder has significant chemical inhomogeneity between and within powder particles, including evidence of gamma ' structural ordering. From solute enrichment remnant from solidification, these regions contain multiple phases including MC, M23C6 and sigma (sigma). Where the local composition is close to the stoichiometric chemistry of the respective phase, they evidently formed without the need for long range diffusional processes that are typically required for their formation. When the powder is heated, these phases, including gamma ', are retained. This study highlights how non-equilibrium characteristics of a gas atomised powder must infleuence microstructural development and, consequently, the selection of subsequent processing steps.

The ability to control the stress-induced phase transformation of the shape memory alloy, NiTi, is an important technological challenge that must be understood for their wide application in devices that can exploit their reversible strain properties. This study elucidates the direct relationship between dislocation density and the martensitic, B19' & R-phase transformations, including its formation temperature from interrupted annealing of rolled NiTi samples. Deformation is shown to determine the enthalpy change required for the B2 -> R -> B19' transformation, with associated transformation temperatures being modifiable via dislocation density and recovery processes. Recovery is shown to be rapid, highly heterogeneous and sensitive to crystal orientation. Grains with a < 100 > direction close to the macroscopic rolling direction recover more rapidly than < 110 > and < 111 > orientated grains. Considered to be governed by processing induced residual stresses and resultant crystallographic dependent annihilation/slip pathways, there are opportunities to tune B2 -> R -> B19' transformation on either a grain-averaged or an orientation dependant per-grain basis.

Objective. Image quality in whole-body MRI (WB-MRI) may be degraded by faulty radiofrequency (RF) coil elements or mispositioning of the coil arrays. Phantom-based quality control (QC) is used to identify broken RF coil elements but the frequency of these acquisitions is limited by scanner and staff availability. This work aimed to develop a scan-specific QC acquisition and processing pipeline to detect broken RF coil elements, which is sufficiently rapid to be added to the clinical WB-MRI protocol. The purpose of this is to improve the quality of WB-MRI by reducing the number of patient examinations conducted with suboptimal equipment. Approach. A rapid acquisition (14 s additional acquisition time per imaging station) was developed that identifies broken RF coil elements by acquiring images from each individual coil element and using the integral body coil. This acquisition was added to one centre’s clinical WB-MRI protocol for one year (892 examinations) to evaluate the effect of this scan-specific QC. To demonstrate applicability in multi-centre imaging trials, the technique was also implemented on scanners from three manufacturers. Main results . Over the course of the study RF coil elements were flagged as potentially broken on five occasions, with the faults confirmed in four of those cases. The method had a precision of 80% and a recall of 100% for detecting faulty RF coil elements. The coil array positioning measurements were consistent across scanners and have been used to define the expected variation in signal. Significance . The technique demonstrated here can identify faulty RF coil elements and positioning errors and is a practical addition to the clinical WB-MRI protocol. This approach was fully implemented on systems from two manufacturers and partially implemented on a third. It has potential to reduce the number of clinical examinations conducted with suboptimal hardware and improve image quality across multi-centre studies.

The mechanisms that govern a previously unexplained hardening effect of a single phase Cu-30wt%Zn α-brass after heating have been investigated. After cold-work, the alloy possesses an increased yield strength and hardening rate only when heat treated to temperatures close to 220 °C, and is otherwise softer. Crystallographic texture and microstructure, explored using electron backscatter diffraction (EBSD), describe the deformation heterogeneity including twin development, as a function of the heat treatment conditions. When heated, an increased area fraction of deformation twins is observed, with dimensions reaching a critical size that maximises the resistance to dislocation slip in the parent grains. The effect is shown to dominate over other alloy characteristics including short range order, giving serrated yielding during tensile testing which is mostly eliminated after heating. In-situ X-ray diffraction during tensile testing corroborates these findings; dislocation-related line broadening and lattice strain development between as-worked and heated α-brass is directly related to the interaction between the dislocations and the population of deformation twins. The experiments unambiguously disprove that other thermally-induced microstructure features contribute to thermal hardening. Specifically, the presence of recrystallised grains or second phases do not play a role. As these heat treatments match annealing conditions subjected to α-brass during deformation-related manufacturing processes, the results here are considered critical to understand, predict and exploit, where appropriate, any beneficial process-induced structural behaviour.

Microstructure-informed crystal plasticity finite element models have shown great promise in predicting plastic and creep deformation in polycrystalline materials. These models can provide substantial insight into the design, fabrication and lifetime assessment of critical metallic components during operation, for instance, in thermal power plants. However, to correctly incorporate damage prediction into models, the microstructural strain simulated at the grain level must be accurately predicted with suitable validation. For this reason, a 3D X-ray Diffraction (3DXRD) experiment was carried out on 316H stainless steel, a material commonly used in thermal power plants, to obtain the per-grain strain response during plastic and creep deformation at 550°C. Several hundred grains within a probed X-ray volume were tracked and measured whilst loading in-situ, obtaining per-grain centre-of-mass positions, crystallographic orientations, and average lattice strain over individual grains. These data were used to calibrate a crystal plasticity model to study the plastic and creep deformation using macroscopic stress-strain and stress-relaxation data. Subsequently, the model was used to predict the average elastic strain in different grains during the cyclic creep experiment, which was validated by 3DXRD datasets. The model results reveal that {100} or {311} grain families are strongly sensitive to microstructure, thereby a polycrystal model that describes specific orientation and neighbourhood characteristics is essential to predict the local response of these grain families. Whereas, self-consistent models are suitable for {110} and {111} grain families. This study shows that only with a suitable calibration of subsurface grain behaviour, crystal plasticity models reveal grain characteristic-dependent micromechanical behaviour.

Thermomechanical processing (TMP) of ferritic–martensitic (FM) steels, such as HT9 (Fe–12Cr–1MoWV) steels, involves normalizing, quenching, and tempering to create a microstructure of fine ferritic/martensitic laths with carbide precipitates. HT9 steels are used in fast reactor core components due to their high-temperature strength and resistance to irradiation damage. However, traditional TMP methods for these steels often result in performance limitations under irradiation, including embrittlement at low temperatures (<~430 °C), insufficient strength and toughness at higher temperatures (>500 °C), and void swelling after high-dose irradiation (>200 dpa). This research aimed to enhance both fracture toughness and strength at high temperatures by creating a quenched and tempered martensitic structure with ultrafine laths and precipitates through rapid quenching and unconventional tempering. Mechanical testing revealed significant variations in strength and fracture toughness depending on the processing route, particularly the tempering conditions. Tailored TMP approaches, combining rapid quenching with limited tempering, elevated strength to levels comparable to nano-oxide strengthened ferritic alloys while preserving fracture toughness. For optimal properties in high-Cr steels for future reactor applications, this study recommends a modified tempering treatment, i.e., post-quench annealing at 500 °C or 600 °C for 1 h, possibly followed by a brief tempering at a slightly higher temperature.

Multiple oxides were observed during the transient oxidation stage of the polycrystalline Ni-based superalloy, RR1000, before a protective Cr2O3 scale formed. Thermogravimetric analysis, synchrotron grazing incidence Xray diffraction, and electron microscopy were performed on samples subjected to isothermal exposures at 800 degrees C for up to 100 h. Transient effects governed the early stages up to 40 h. NiO, spinels (NiCr2O4, (Ni,Co)(Cr,Co)2O4), Cr2O3/(Cr0.88Ti0.12)2O3, NiTiO3, and CrTaO4 formed during the initial stage with pseudo-linear kinetics. At the onset of parabolic kinetics, extensive Cr2O3 and TiO2 growth dominated scale formation with the former emerging as the major passivating oxide.

A novel complex-phase steel alloy is conceived with a deliberately unstable austenite, $\gamma$, phase that enables the deformation-induced martensitic transformations (DIMT) to be explored at low levels of plastic strain. The DIMT was thus explored, in-situ and non-destructively, using both far-field Three-Dimensional X-Ray Diffraction (3DXRD) and Electron Back-Scatter Diffraction (EBSD). Substantial $\alpha'$ martensite formation was observed under 10% applied strain with EBSD, and many $\varepsilon$ grain formation events were captured with 3DXRD, indicative of the indirect transformation of martensite via the reaction $\gamma \rightarrow \varepsilon \rightarrow \alpha'$. Using $\varepsilon$ grain formation as a direct measurement of $\gamma$ grain stability, the influence of several microstructural properties, such as grain size, orientation and neighbourhood configuration, on $\gamma$ stability have been identified. Larger $\gamma$ grains were found to be less stable than smaller grains. Any $\gamma$ grains oriented with {100} parallel to the loading direction preferentially transformed with lower stresses. Parent $\varepsilon$-forming $\gamma$ grains possessed a neighbourhood with increased ferritic/martensitic volume fraction. This finding shows, unambiguously, that $\alpha$/$\alpha'$ promotes $\varepsilon$ formation in neighbouring grains. The minimum strain work criterion model for $\varepsilon$ variant prediction was also evaluated, which worked well for most grains. However, $\varepsilon$-forming grains with a lower stress were less well predicted by the model, indicating crystal-level behaviour must be considered for accurate $\varepsilon$ formation. The findings from this work are considered key for the future design of alloys where the deformation response can be controlled by tailoring microstructure and local or macroscopic crystal orientations.

The structural performance of polycrystalline alloys is strongly controlled by the characteristics of individual grains and their interactions, motivating this study to understand the dynamic micromechanical response within the microstructure. Here, a high ductility single-phase ferritic steel during uniaxial deformation is explored using three-dimensional X-ray diffraction. Grains well aligned for dislocation slip are shown to possess a wide intergranular stress range, controlled by per-grain dependent hardening activity. Contrariwise, grains orientated poorly for slip have a narrow stress range. A grain neighbourhood effect is observed of statistical significance: the Schmid factor of serial adjoining grains influences the stress state of a grain of interest, whereas parallel neighbours are less influential. This phenomenon is strongest at low plastic strains, with the effect diminishing as grains rotate during plasticity to eliminate any orientation dependent load shedding. The ability of the ferrite to eliminate such neighbourhood interactions is considered key to the high ductility possessed by these materials.

This study is to explore an economically attractive and technically feasible processing method for oxide-nanoparticle strengthened alloys for fusion reactor application. Despite many scientific merits of the advanced oxide-dispersion strengthened (ODS) alloys, such as the nanostructured ferritic alloy (NFA) 14YWT, the only viable production path for a high-quality NFA is the high-power mechanical alloying process. This process is often a multi-day high-speed ball milling of alloy powder with a small quantity of yttria (Y2O3) powder, followed by the milled-powder consolidation using extrusion or other methods and additional thermomechanical processing (TMP) for property control. This complex production path, including the low-temperature mechanical alloying in particular, has limited technical advancement toward the cost-effective and scale-up production of ODS alloy components. To overcome such a practical limitation, we proposed to explore alternative low-cost processing routes using traditional thermomechanical processing (TMP) method only. A series of continuous TMP cycles, which were designed to impose high-temperature severe plastic deformation (HT-SPD) conditions to the consolidated powder mixtures, were applied to achieve the effective distribution of oxide particles in nanograin structure and thus desirable mechanical properties. Since the reduced-activation ferritic-martensitic (RAFM) alloy powders (Fe-10Cr and Fe-14Cr alloys with various Y contents) are available in our inventory, we focused to utilize the new solid-state synthesis approach for controlling oxide (oxygen source) dissolution and nanoscale clustering in nanograin structure in those alloys. A combination of powder consolidation at 900°C and continuous thermomechanical activation at 600°C yielded two essential ODS alloy microstructure contents–nanograin structure and nanoparticle distribution–and thus demonstrated a good combination of strength and ductility.

Samples of the Ni-based superalloy, RR1000, were exposed to 98

This study explores cardiovascular stents fabricated using laser powder bed fusion (LPBF); an emerging method to offer patient-specific customisable parts. Here, the shape memory alloy NiTi, in a near equiatomic composition, was investigated to deconvolve the material response from macroscopic component effects. Specifically, stress-geometry interactions were revealed, in-situ, for a minaturised cardiovascular stent subjected to an externally applied cylindrical stress whilst acquiring synchrotron X-ray imaging and diffraction data. The approach enabled the collection of spatially resolved micromechanical deformation data; the formation of stress-induced martensite and R-phase was evident, occurring in locations near junctions between stent ligaments where stress concentrations exist. In the as-fabricated condition, hardness maps were obtained through nanoindentation, demonstrating that the localised deformation and deformation patterning is further controlled by porosity and microstructural heterogeneity. Electron backscatter diffraction (EBSD) supported these observations, showing a finer grain structure near stent junctions with higher associated lattice curvature. These features, combined with stress concentrations when loaded will initiate localised phase transformations. If the stent was subjected to repeated loading, representing in-vivo conditions, these regions would be susceptible to cyclic damage through transformation memory loss, leading to premature component failure. This study highlights the challenges that must be addressed for the post-processing treatment of LABF-processed stents for healthcare-related applications.

The industrialization of Laser Additive Manufacturing (LAM) is challenged by the undesirable microstructures and high residual stresses originating from the fast and complex solidification process. Non-destructive assessment of the mechanical performance controlling deformation patterning is therefore critical. Here, we use Dark Field X-ray Microscopy (DFXM) to map the 3D subsurface intragranular orientation and strain variations throughout a surface-breaking grain within a directed energy deposition nickel superalloy. DFXM results reveal a highly heterogenous 3D microstructure in terms of the local orientation and lattice strain. The grain comprises ≈ 5 μm-sized cells with alternating strain states, as high as 5 ×10−3, and orientation differences <0.5°. The DFXM results are compared to Electron Backscatter Diffraction measurements of the same grain from its cut-off surface. We discuss the microstructure developments during LAM, rationalising the development of the deformation patterning from the extreme thermal gradients during processing and the susceptibility for solute segregation.

Improved oxidation kinetics for a polycrystalline Ni-based superalloy used in turbine disc applications has been shown to be possible by controlling the heating rate of the first thermal exposure to 5 °C min −1 . The beneficial effect arises from the formation of a protective layer of NiCr 2 O 4 , instead of the more usually formed doped Cr 2 O 3 . This study shows that it was possible to form the NiCr 2 O 4 at temperatures up to 725 °C, within the operational conditions for this alloy, and that at higher temperatures Cr 2 O 3 formed. The improvements in alloy performance extended to the internal oxidation processes where reduced depths of degradation were observed. It is demonstrated here that Al 2 O 3 formation is less thermodynamically stable when the highly protective NiCr 2 O 4 oxide is present at the alloy surface compared to the doped Cr 2 O 3 . Synchrotron XRD was performed on samples removed during the heating stage and provided evidence of the oxidation sequence occurring, enabling refinement in the thermodynamic calculations and suggesting an additional route to the formation of the NiCr 2 O 4 .

Predictions of material activity in commercial fusion conditions predominantly rely on computational methods, due to a lack of data on long-term effects of high-energy neutron irradiation on structural steels. Consequently, this could result in a bias due to uncertainties in nuclear data used. This work focused on modelling neutron activation of four structural steels in a fusion reactor environment after 20 years of operation. Eurofer, F82H and G91, were assessed as candidate in-vessel materials, whereas SS316L(N)-IG was solely modelled in the vacuum vessel. Activation calculations were performed using the inventory code FISPACT-II using inputs from Monte-Carlo transport simulations performed with OpenMC. The study employed a one-dimensional reactor model with a Helium-Cooled Pebble Bed (HCPB) tritium-breeding blanket design. With the XSUN-2022 code package, a nuclear data sensitivity and uncertainty analysis on production cross-sections of relevant radio-nuclides was carried out. Eurofer and F82H steels exhibited significantly higher resistance to neutron activation than G91 and SS316L(N)-IG. At 100 years after shutdown, none of the steels reached UK low-level waste (LLW) activity levels in the first wall. In the rear of the back-support structure (BSS) of the reactor blanket, all assessed steels reached LLW levels within approximately 30 to 45 years of reactor shutdown. It was found that the vacuum vessel (SS316L(N)-IG) would not be classifiable as LLW for several centuries. Dominant radio-nuclides for each material were identified with FISPACT-II to carry out the uncertainty analyses. The calculated uncertainties were too small to affect the waste disposal options for the first wall within 100 years, but the time-to-reach LLW for BSS and vacuum vessel steel could be uncertain by up to approximately 3 and 6 years, respectively.

A crystallography-based method is presented for the critical appraisal of possible mechanisms that trigger the formation of secondary grains during directional solidification. The method permits an analysis of a large population of defects, while avoiding the pitfalls of the metallographic sectioning approach that is affected by dendrite stereology. Here, the nickel-base superalloy CMSX-4, an alloy commonly used for single crystal turbine blade applications, is studied. All secondary grains originate exclusively at the external surface and when the off-axial primary ⟨ 0 0 1⟩ crystal orientations are measured, are evident at both the converging and diverging dispositions of the single crystal primary dendrites without a noticeable bias. Almost all of the secondary grains have low misorientations, with an average misorientation between 5 to 15 deg. No systematic deviation between the individual ⟨ 0 0 1⟩ orientations of the secondary grain and the single crystal is observed. A significant twist contribution about an axis within 30 deg from one of the secondary arms occurs when primary arms converge on the external surface, but both twist and tilt prevail for the diverging case. Both nucleation and buoyancy driven thermo-solutal convection can be eliminated as potential mechanisms. Thermo-mechanical deformation is deduced to be the most likely mechanism; deformation must originate in the vicinity of the primary dendrite tips. It is proposed that dendrite deflection arises primarily from the resistance encountered by the primary tips with the external surface during axial contraction in the presence of a dominant vertical thermal gradient.

This article proposes a generalizable, data-driven framework for qualifying laser powder bed fusion additively manufactured parts using part-specific in situ data, including powder bed imaging, machine health sensors, and laser scan paths. To achieve part qualification without relying solely on statistical processes or feedstock control, a sequence of machine learning models was trained on 6299 tensile specimens to locally predict the tensile properties of stainless-steel parts based on fused multi-modal in situ sensor data and a priori information. A cyberphysical infrastructure enabled the robust spatial tracking of individual specimens, and computer vision techniques registered the ground truth tensile measurements to the in situ data. The co-registered 230 GB dataset used in this work has been publicly released and is available as a set of HDF5 files. The extensive training data requirements and wide range of size scales were addressed by combining deep learning, machine learning, and feature engineering algorithms in a relay. The trained models demonstrated a 61% error reduction in ultimate tensile strength predictions relative to estimates made without any in situ information. Lessons learned and potential improvements to the sensors and mechanical testing procedure are discussed.