I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[33667]
Open Access
Abstract: The use of conventional zirconium alloys at temperatures above 400 °C is limited by high temperature strength and creep resistance. This has prevented the consideration of zirconium alloys for fusion and Generation IV fission plant designs operating at 500 °C–1000 °C. The physical metallurgy of zirconium is similar to titanium which has seen alloying advances allowing application temperatures up to 600 °C. Although the oxidation resistance of zirconium-based alloys is expected to be poor, in a water environment, new Generation-IV and fusion reactors are designed to operate using alternative coolants such as liquid metals and molten salts. Therefore, a new class of zirconium alloys in the Zr-Al-Sn-(Si,Cr,V) system, designed by analogy to near-
titanium alloys, were synthesised by arc melting and processed in a sequence of homogenisation, hot/cold rolling, recrystallisation, and ageing treatments. Microscopy and diffraction identified a refined fully lath grain structure reinforced by nanoscale lamellar or discrete coherent Zr3Al precipitates, with morphology and crystal structure differing with ageing times. Additionally alloying with Si, Cr, and V respectively leads to Zr2Si, ZrCr2, and ZrV2 incoherent precipitates. Tensile testing revealed a strengthening effect by Al, but with significant changes to ductility on ageing depending on the evolution of Zr3Al. Creep testing showed creep rates orders of magnitude better than conventional Zircaloy-4 and nuclear ferritic/martensitic steels, approaching near-
Ti alloys. The present work offers new insights and perspectives into how high-temperature zirconium alloys might be designed to meet the requirements for fusion and Gen-IV fission.
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Mar 2026
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[31134]
Open Access
Abstract: Growth kinetics and orientation selection play a significant role in microstructure evolution during metal solidification, while gravity-induced convection adds significant complexity to the process. In-situ, time-resolved X-ray imaging of solidifying grain-refined Al–20 wt.% Cu alloy onboard the MASER-13 sounding rocket enabled the study of equiaxed dendrite growth under diffusion-controlled conditions, eliminating the influence of gravity. A machine learning-enabled analytical pipeline was developed to extract and evaluate the spatiotemporal behaviour of a large number of individual dendrites, including their growth characteristics, rotations and interactions. Post-flight synchrotron X-ray computed tomography and electron backscatter diffraction were used to reconstruct the three-dimensional dendrite structure with embedded details of crystallographic orientations. Correlated data analysis confirmed that most dendrites grew along directions parallel to the {100} plane under highly isothermal, diffusion-controlled conditions. However, growth along atypical directions was also observed, even in this simplified regime. The benchmark data revealed variation in dendrite arm evolution, influenced by local grain interactions and crystallographic orientation selection. It is shown that the equiaxed grains have random crystallographic orientations and evidence suggests that these survive from shortly after nucleation in the bulk liquid under microgravity conditions. The data processing protocols demonstrated here highlight the potential of integrating advanced experimental techniques with modern data science approaches to analyse solidification microstructure formation in metallic alloys under terrestrial and microgravity conditions.
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Oct 2025
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[36212]
Abstract: Fe-rich intermetallic compounds (IMCs) are a persistent challenge in the recirculation of secondary aluminium alloys. Despite significant research effort, largely via post-solidification studies, the mechanisms governing IMC phase selection in higher-Fe (
wt.%), recycled Al alloys and how they can be controlled to facilitate more benign IMC species and/or morphologies remain poorly understood. This creates barriers to compositional and process design for more Fe-tolerant alloys. In this paper, we present a systematic real-time investigation of IMC formation, phase selection and morphological evolution in recycled 3xx series Al alloys with elevated Fe concentrations (up to 2.5 wt%), using in situ synchrotron X-ray radiography. Coupled with thermodynamic simulations, we develop a method to reliably estimate the formation temperatures of primary
-AlFeSi and
-AlFeSi IMCs, and show direct insights into their formation sequence and kinetics. Contrary to widely held assumptions based on low Fe-containing (
0.6 wt%) primary alloys, we show that in recycled alloys containing higher Fe concentrations, increased cooling rate significantly promotes the formation of the more anisotropic
-AlFeSi (over the more compact
-AlFeSi), which however can be fully suppressed at slow cooling. We propose how a solute-suppression mechanism kinetically controls the
/
IMC phase evolution. Further, we reveal and quantify a faceted-to-non-faceted morphological transition of
-AlFeSi from a faceted polyhedral to non-faceted near-equiaxed dendritic morphology. This transition is governed by an interplay between solidification velocity and liquid undercooling at the local IMC/liquid interfaces. This study provides insights into how solidification conditions may be leveraged to improve microstructural control in high Fe-containing recycled alloys.
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Oct 2025
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[31855]
Open Access
Abstract: Directed energy deposition (DED) laser additive manufacturing (AM) is a promising technique for building complex components and performing repair applications. However, large defects can form through coalescence of argon bubbles from the feedstock powder, potentially reducing end-component mechanical performance. Here, we used correlative high-speed synchrotron X-ray and infrared imaging, coupled with multiphysics modelling to develop a strategy to control defect formation. We demonstrate that the bubble dynamics can be controlled by appropriately modulating the laser power, temporarily disrupting the Marangoni flow, enabling bubble release. The bubble control mechanisms discovered here provide a way to achieve defect-lean AM.
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Sep 2025
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I12-JEEP: Joint Engineering, Environmental and Processing
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J. R.
Miller
,
H. C.
Cole
,
J. M.
Hogg
,
J.
Pitchforth
,
L. D.
Connor
,
P.
Vacek
,
S.
Neumeier
,
N. L.
Church
,
P. A.
Midgley
,
D. M.
Collins
,
C. M. F.
Rae
,
H. J.
Stone
Diamond Proposal Number(s):
[31966]
Open Access
Abstract: Single crystal Ni-base superalloys, like many materials containing an A1 structured phase, demonstrate additional forbidden reflections in diffraction experiments. These additional reflections are most commonly attributed to the presence of chemical short-range order, or to thin foil effects in transmission electron microscopy. In this study, transmission electron diffraction and synchrotron X-ray diffraction were used to interrogate the deformation mechanics in a single crystal Ni-base superalloy at room temperature. Additional reflections were observed around those from the A1 phase in both diffraction experiments, arising from relrods along . These relrods were linked to the formation of extensive intrinsic stacking faults (ISFs) within the A1 phase, giving rise to local disorder and a relaxation of the Bragg condition. This study represents the first use of single crystal X-ray diffraction to characterise forbidden reflections in A1 structures from bulk specimens, thereby discounting thin foil effects completely.
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Sep 2025
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I11-High Resolution Powder Diffraction
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Kan
Ma
,
Pedro A.
Ferreiros
,
Thomas W.
Pfeifer
,
Robert G.
Abernethy
,
Sophia
Von Tiedemann
,
Nianhua
Peng
,
Graeme
Greaves
,
Colin
Ophus
,
Kai
Sun
,
Anamul H.
Mir
,
Lumin
Wang
,
Shasha
Huang
,
Shijun
Zhao
,
Patrick E.
Hopkins
,
Christopher D.
Hardie
,
Alexander J.
Knowles
Diamond Proposal Number(s):
[32708]
Open Access
Abstract: Intermetallic dispersion-strengthening (IDS) using nano-scale coherent intermetallic precipitates offers a potent strategy to produce high-strength and radiation-resistant steels, whilst addressing the manufacturability challenges of analogous oxide dispersion-strengthened (ODS) steels. However, their performance with intermetallic stability under irradiation damage, such as radiation-induced hardening (RIH), whilst hypothesised, is undemonstrated. Here, we report on a model IDS α(A2) + α’(L21) Fe-Ni-Al-Ti ferritic superalloy, which exhibits exceptional resistance to RIH with near-zero hardening after irradiation at 300°C 1 dpa, in contrast to significant RIH in a counterpart coarse precipitate alloy (increase in nano-hardness of 1.0 GPa) and Eurofer97 (0.7 GPa). This irradiation resistance is attributed to the high density of semi-coherent precipitate-matrix interfaces, and partial-disordering L21->B2 which causes a decrease in anti-phase boundary energy. High interface density with localised interfacial strain offers effective sinks, suppressing defect populations compared to the counterpart with lower interface density. Meanwhile, atomic resolution spectroscopy and irradiation with in-situ transmission electron microscopy show that the disordering stems from Al-rich and Ti-rich sublattices mixing in the initial L21-Ni2AlTi structure below 500°C, forming metastable B2-Ni(Al,Ti). Combined, the high interface density and radiation-induced intermetallic disordering underpin the remarkable radiation tolerance, demonstrating the IDS concept as a promising radiation-resistant materials design strategy.
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May 2025
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[30553]
Open Access
Abstract: BiFeO3-BaTiO3 (BF-BT) solid solutions have great potential as high-temperature piezoelectric transducers and energy storage dielectrics. However, the effects of donor doping in BF-BT on the local chemical heterogeneity and corresponding control of ferroelectric properties are not well investigated. In this study, it is shown that substitution of Nb5+ for Fe3+ at a concentration of only 0.1 at% in 0.75BF-0.25BT ceramics can induce pronounced core-shell microstructural features, which are not evident for pure BF-BT ceramics or those doped with 0.1 at% Nb5+ for Ti4+. The spatial distribution of Nb, confirmed by Nano-SIMS with exceptional resolution and sensitivity, reveals the role of Nb as an aliovalent solute that inhibits chemical homogenization, stabilizing the formation of Bi-, Fe-enriched core and Ba-, Ti-enriched shell regions at high temperatures, and reducing inter-diffusion during sintering. Electric field-induced domain switching and lattice strain measurements, obtained by in-situ high-energy synchrotron X-ray diffraction, revealed the effects of elastic constraint between the core and shell regions, which degraded the dielectric, ferroelectric, and piezoelectric properties. In contrast, substitution of 0.1 at% Nb on the Ti4+ site gave rise to more homogeneous materials and induced a softening effect with enhanced functional properties. This study provides an advanced investigation into the effects of trace amounts of donor dopant in BF-BT ceramics and offers valuable insights into optimizing doping strategy to control their microstructure and functional properties.
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Mar 2025
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I15-Extreme Conditions
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Diamond Proposal Number(s):
[31608]
Open Access
Abstract: Electric field-induced phase transition behaviour, extensively studied in perovskite-structured ceramics, has not been previously reported in unfilled tetragonal tungsten bronze (TTB) structured ceramics. In this work, we present the first investigation of electric field-induced phase transitions in high entropy designed unfilled TTB structured Ca0.25Sr0.25Ba0.25Pb0.25Nb2O6 (CSBP) ceramics using dielectric and ferroelectric characterization techniques. The findings reveal that field-induced polarization in the CSBP ceramics evolve from irreversible to reversible with increasing temperature. Furthermore, relaxor ferroelectric behaviour was observed in the ceramics, attributed to the A-site cation disorders in the unfilled TTB structure, facilitated by the high entropy design. The absence of non-180° domain switching was indicated by microstructural observations and analysis of the strain-electric field (S-E) response. In-situ poling synchrotron studies and experimental S-E response measurements revealed an electrostrictive behaviour characterized by an electrostrain not originating from macroscopic structural transformations or long-range domain switching but more likely contributed by the reorientation of polar nanoregions. The results obtained provide a foundation for future studies investigating the electric field-induced phase transition and domain switching behaviour in the unfilled TTB structured ceramics.
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Nov 2024
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I12-JEEP: Joint Engineering, Environmental and Processing
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Kai
Zhang
,
Tim
Wigger
,
Rosa
Pineda
,
Simon A.
Hunt
,
Ben
Thomas
,
Thomas
Kwok
,
David
Dye
,
Gorka
Plata
,
Jokin
Lozares
,
Inaki
Hurtado
,
Stefan
Michalik
,
Michael
Preuss
,
Peter D.
Lee
,
Mohammed A.
Azeem
Diamond Proposal Number(s):
[23749]
Abstract: Microstructure evolution during high-strain rate and high-temperature thermo-mechanical processing of a 44MnSiV6 microalloyed steel is investigated using in situ synchrotron high-energy powder X-ray diffraction. The conditions selected replicate a newly developed near solidus high-strain rate process designed for reducing raw material use during the hot processing of steels. High temperatures (exceeding 1300 °C) and high strain rate
= 9 s-1 processing regimes are explored. The lattice strains and dislocation activity estimated from diffraction observations reveal that the microstructure evolution is primarily driven by dynamic recrystallisation. A steady-state stress regime is observed during deformation, which develops due to intermittent and competing work hardening and recovery processes. The texture evolution during the heating, tension, shear deformation and cooling stages is systematically investigated. The direct observation of phase evolution at high-temperature and high-strain rate deformation enables a comprehensive understanding of new manufacturing processes and provides deep insights for the development of constitutive models for face-centred cubic alloys.
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Aug 2024
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[27571]
Open Access
Abstract: Using synchrotron X-ray diffraction, tomography and machine-learning enabled phase segmentation strategy, we have studied under operando conditions the nucleation, co-growth and dynamic interplays among the dendritic and multiple intermetallic phases of a typical recycled Al alloy (Al5Cu1.5Fe1Si, wt.%) in solidification with and without ultrasound. The research has revealed and elucidated the underlying mechanisms that drive the formation of the very complex and convoluted Fe-rich phases with rhombic dodecahedron and 3D skeleton networks (the so-called Chinese-script type morphology). Through statistical microstructural analyses and numerical modelling of the ultrasound melt processing, the research has demonstrated that a short period of ultrasound processing of just 7s in the liquid state is able to reduce the average size of the α-Al dendrites and the Fe-containing intermetallic phases by ∼5 times compared to the cases without ultrasound. This work has provided more new insights on quantitatively understanding of the formation of convoluted morphology of intermetallic phases in 4D domain and the beneficial effects of applying ultrasound to recycled Al alloys, which are directly relevant to industrial practice.
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Aug 2024
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