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Open Access
Abstract: Non-destructive evaluation (NDE) is used to detect and characterise defects in safety-critical components. This paper focuses on manual pulse-echo ultrasonic testing applied to the sizing of surface-breaking crack-like defects. In the field, practitioners often use A-scans from single element, pulse-echo ultrasonic testing. Machine learning, and in particular neural networks, have huge potential for applications to NDE-type problems due to their ability to recognise patterns from signals. Accurate predictions require large, labelled databases yet there is a paucity of such ultrasonic data for surface-breaking thermally fatigued cracks. To address this deficit, this work demonstrates that a database composed entirely of simulated, synthetic A-scans provides promising predictions on measured data. Crack height predictions with a mean absolute error of around 0.124 mm are achieved for measured data (on cracks between 0.5 mm and 4 mm). When tested on simulated A-scans, both height and tilt angle predictions are extremely accurate (to within 0.035 mm and 0.41°, respectively). To achieve such accuracy the in-situ inspection techniques were mimicked, with particular attention paid to the characteristics of the thermally fatigued crack species, and the single element transducer and its input signal. The details of the finite element simulations that generated the database are presented here. The work outlined in this paper shows that A-scans can be used to size defects using neural networks trained entirely on synthetic data, informed by experimental measurements, with potential applications for improving the efficiency of sizing cracks in-situ.
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Oct 2026
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E02-JEM ARM 300CF
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Liliana
Romero Resendiz
,
Jesus Israel S.
Palafox
,
Wei
Xiong
,
Yan
Lu
,
Chenyang
Li
,
Wei
Chen
,
Ziyang
Fan
,
Matthew C.
Spink
,
Mohsen
Danaie
,
Wu
Gong
,
Stefanus
Harjo
,
Xun-Li
Wang
,
Yuntian T.
Zhu
,
Muhammad
Naeem
Diamond Proposal Number(s):
[40350]
Open Access
Abstract: Precipitates in structural alloys are conventionally understood as passive obstacles to dislocation motion. Here we show that semi-coherent hexagonal close-packed precipitates in a low-stacking-fault-energy Ni50Co30Ru20 multi-principal element alloy cooperate with planar-fault plasticity in the face-centered cubic matrix. In-situ neutron diffraction, high-resolution electron microscopy, and first-principles calculations reveal that these precipitates interact with and locally modify Shockley-partial-mediated fault structures, are associated with confined, deformation-related interfacial stacking rearrangement, and generate heterogeneous stress fields that sustain work hardening. Phase-resolved diffraction shows that the precipitates yield at an applied stress of ∼1020 MPa and that the load they carry directly is bounded at ∼6–10% of the yield strength, so their contribution mainly acts through the precipitate-matrix interfaces, resulting in a tensile strength of 1038 MPa and 39% uniform elongation. These findings establish a design strategy: coupling low fault energy with deformable phase heterogeneity amplifies planar-fault-mediated strain hardening.
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Sep 2026
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I12-JEEP: Joint Engineering, Environmental and Processing
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Kai
Zhang
,
Harry E.
Chapman
,
Imogen
Cowley
,
D. Graham
Mccartney
,
Shishira
Bhagavath
,
Samuel J.
Clark
,
Alexander
Rack
,
Robert C.
Atwood
,
Martyn A.
Jones
,
Chinnapat
Panwisawas
,
Chu Lun Alex
Leung
,
Junji
Shinjo
,
Peter D.
Lee
Diamond Proposal Number(s):
[31855, 30735]
Abstract: Porosity in laser powder-based directed energy deposition (DED) additive manufactured alloy components may compromise mechanical performance. This study demonstrates how a 0.2 wt.% addition of micron-sized La2O3 particles blended with gas atomised RR1000 Ni-based superalloy powder affect pore evolution, reducing the occurrence of porosity, especially large pores. Using correlative in situ high-speed synchrotron X-ray and infrared imaging coupled with multiphysics modelling, we reveal the underlying melt flow and pore evolution behaviour with and without La2O3 additions. The particulate addition produces a pore-lean build with notably fewer large pores. We propose this occurs through two mechanisms involving La2O3 on the surface altering thermal and fluid flow conditions within the melt pool through: (i) a reduction of melt pool surface tension gradient, and (ii) an increase in melt pool absorptivity. Additionally, we find that La2O3 enhances powder capture efficiency.
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Sep 2026
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I12-JEEP: Joint Engineering, Environmental and Processing
|
J. F. S.
Markanday
,
D. M.
Collins
,
N.
D'Souza
,
G. J.
Wise
,
N. L.
Church
,
J. R.
Miller
,
J. J. C.
Pitchforth
,
A. S.
Wilson
,
L. D.
Connor
,
S.
Michalik
,
N. G.
Jones
,
P.
Kontis
,
K. A.
Christofidou
,
H. J.
Stone
Diamond Proposal Number(s):
[33375]
Open Access
Abstract: This study investigates the laser-powder bed fusion (L-PBF) Ni-based superalloys IN713LC and STAL 15DE to reinterpret strain-age macrocracking (SAC) as a coupled process linking non-equilibrium
γ
′
precipitation, internal stress development, and grain-boundary phase transformations. In contrast to frameworks that predict SAC susceptibility from equilibrium quantities such as
γ
′
phase fraction and lattice misfit, the present work shows that the mechanical driving force is generated dynamically during heating from the as-built condition, as the supersaturated matrix evolves. In the as-built condition, IN713LC retains
γ
′
in a highly non-equilibrium state, which subsequently develops a net tensile stress during heating that progressively relaxes until reaching 900 °C. The
γ
/
γ
′
misfit remains positive throughout the cracking-relevant temperature interval, decreasing towards zero only as this stress state relaxes. This demonstrates that a positive misfit alone is insufficient to prevent macrocracking under additive manufacturing (AM) relevant reheating conditions. This mechanism is not replicated in STAL 15DE as no
γ
′
is present in the as-built condition. In both alloys, metastable MC-type carbides present in the as-built condition decompose during heating, coinciding with the formation of M23C6. This carbide transformation occurs over the same temperature interval as precipitation-associated volumetric strain and the dynamic development and relaxation of the internal stress state. Atom probe tomography further reveals that grain boundaries, while chemically distinct in the as-built state, undergo extensive solute redistribution during thermal-mechanical exposure, consistent with reduced intergranular cohesion. Ultimately, these results indicate that intergranular SAC is governed by a coupled mechanism: precipitation-associated volumetric strain provides the mechanical driving force for damage, while concurrent changes in grain-boundary phases degrade the cohesion of the boundary itself.
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Sep 2026
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I11-High Resolution Powder Diffraction
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Open Access
Abstract: Nanostructuring has been proposed for alloys to be used in future fusion reactors, as a high grain boundary density may act as a sink for irradiation-induced defects, enhancing irradiation tolerance. We use molecular dynamics to model collision cascades in nanocrystalline iron and compare the damage evolution to that observed in initially perfect, single crystalline iron. The nanocrystalline material is generated either by Voronoi tessellation or severe plastic shearing. Upon irradiation, we observe grain coarsening, with all initially nanocrystalline simulation cells becoming single crystalline above 2 displacements per atom (dpa). Above a damage dose of 1 dpa, nanocrystalline cells show a lower dislocation density and lower lattice swelling than their initially pristine counterparts. Experimental X-ray diffraction data is collected from nanocrystalline iron samples made by high pressure torsion and subsequently subjected to self-ion irradiation. Line profile analysis data agrees with the trends observed in the atomistic simulations, revealing the presence of an irradiation-induced annealing process, with a clear increase in grain size and reduction in micro-strain with increasing dose.
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Sep 2026
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B16-Test Beamline
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Diamond Proposal Number(s):
[37827]
Open Access
Abstract: Auxetic behavior provides a route to increase specific energy absorption and useful cushioning deformation in applications that include medical, sports and vehicular engineering. To be effective, the development of auxetic behavior typically requires a structure with many small unit cells. However, improved manufacturing resolution affords better, more consistent behavior to larger unit cells. These factors are inter-linked by sub-cell strains, where the strain patterns in loaded re-entrant auxetics are currently not well understood. This study provides the first analysis of the use of X-ray diffraction to understand the sub-cell strain behavior in re-entrant auxetic structures. The use of a synchrotron enabled unparalleled resolution of in-situ strain data, where re-entrant cells were examined based on a range of imposed concave fillets, from zero to 0.75 of cell size. The experimental data demonstrated that reducing the fillet radius reduced the 95th percentile strain exhibited by the auxetic by 49%, thereby widening the elastic domain of the material. The experimental data were compared with a homogenization modelling approach that varied the cell count, which revealed a Poisson’s ratio reduction, and therefore an improvement in auxetic response, from -0.13 to -0.39 when using 1 to 10 cells, highlighting the benefit of creating auxetics with more cells. The combination of experimental and modelling approaches allowed numerical comparison of cell scales and cell counts to identify ideal scales for manufacturing. These results supported the development of a new set of design guidelines for the design and production of practical auxetic metamaterials and ensure right-first-time manufacturing.
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Sep 2026
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I13-2-Diamond Manchester Imaging
|
Diamond Proposal Number(s):
[37837, 33810]
Open Access
Abstract: Braid angle is a key design variable for braided composite tubes, yet its role in governing damage evolution in multilayer tubular architectures under torsion remains insufficiently understood. Here, time-resolved in-situ synchrotron X-ray computed tomography (CT) has been used to investigate the torsional behaviour of double-layer 1/1 braided CFRP tubes with braid angles of 30° (DL30), 45° (DL45) and 60° (DL60). Increasing braid angle progressively increased wall thickness and tow crimp, while the effective fibre volume fraction varied only modestly and non-monotonically. These architectural changes produced distinct mechanical responses: DL45 and DL60 exhibit higher tube-level torsional stiffness whereas DL30 displays the highest shear modulus and torsional strength. Damage accumulation is strongly braid-angle dependent. At higher strain levels, intra-tow cracking, inter-tow debonding and inter-laminar debonding all markedly reduce as braid angle increases. The predominant damage mechanism also changes: DL30 develops a rapidly connected damage network (intra-tow cracking and inter-tow/laminar debonding) promoting microscale fibre kinking/buckling and further fibre breakage, leading to an abrupt post-peak loss of strength; DL45 showed more distributed damage accumulation and the highest post-peak strength; while DL60 exhibited delayed, weakly connected damage evolution with the lowest overall level of damage accumulation. These results suggest that angle-graded multilayer designs could combine lower-angle regions for reduced tow crimp, higher shear modulus and strength, with intermediate or higher-angle regions for damage suppression and stable post-peak performance.
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Sep 2026
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I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[38691]
Abstract: Metallic materials with nanolamellar structures, such as pearlitic steels, exhibit high strength with appropriate ductility. Considering the potential ability of such nanolamellar structures to break the traditional strength-ductility trade-off in metallic alloys, this study aims at developing a unique nanolamellar structure with superior micromechanical properties by combining two different high-entropy alloys (HEAs). Al0.1CoCrFeNi with the face-centered cubic (FCC) structure is combined with TiZrHfNbTa with the body-centered cubic (BCC) structure using high-pressure torsion (HPT) of half discs of each alloy. That way, a layered hybrid structure was formed, with layer thickness down to about 61 nm. The BCC/FCC nanolamellar hybrid structure exhibits an exceptional combination of properties with an ultimate tensile strength of 2.4 GPa, a maximum bending strength of 4.0 GPa, and a hardness of 740 Hv, while retaining some ductility/plasticity under both tensile and bending loads. Detailed analyses by synchrotron diffraction, electron microscopy and atom probe tomography suggests that these high strength and hardness, which are superior to those of nanostructured HEAs, result from: (i) extreme grain boundary strengthening from nanograins with a mean size of 22 nm, (ii) presence of defects such as dislocations in FCC and BCC, stacking faults in FCC and twins in FCC, and (iii) interphase hardening from BCC/FCC nanolamellar boundaries with about 30% contribution to the total hardness. This work demonstrates that combining two HEAs using HPT into a defect-rich hybrid nanolamellar composite forms a promising synergy of ultrahigh strength and reasonable ductility/plasticity.
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Sep 2026
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|
B16-Test Beamline
|
Diamond Proposal Number(s):
[37812]
Open Access
Abstract: Carbon nanotube wires are promising candidates for next-generation beam instrumentation because of their ultralow mass, radiation tolerance, and potential for stable mechanical and structural behaviour under extreme operating conditions. However, their performance is strongly influenced by catalyst contamination, graphitic disorder, and residual microstrain inherited from fabrication and bundle architecture. Understanding how these factors vary across different CNT wire architectures is essential for developing reliable low-density conductors for future accelerator systems.
This study presents a comparative structural and mechanical investigation of carbon nanotube wires spanning distinct nanotube types, fabrication routes, and diameters from
10
μ
m
to
50
μ
m
, examined before and after nitric-acid purification and twist fixation. Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, tensile testing, and in situ synchrotron X-ray diffraction were combined to quantify graphitic order, lattice spacing, and spatial heterogeneity. Strong architecture-dependent behaviour was observed. The
10
μ
m
wire exhibited compressed basal-plane spacing and large spatial variability, whereas the
50
μ
m
multi-walled-dominant wire remained close to relaxed turbostratic spacing. Purification reduced impurity content, improved graphitic coherence, and enhanced tensile stiffness, including an increase from 30.8 GPa to 68.4 GPa in the
10
μ
m
wire, while preserving the underlying hierarchy of residual strain across suppliers.
The results demonstrate that purification improves structural uniformity and mechanical consistency, but that the dominant lattice strain state is primarily governed by nanotube architecture and bundle topology rather than chemical treatment.
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Sep 2026
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I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[38206]
Open Access
Abstract: Masonry structures predominantly work under compression; elasticity in constituent materials is therefore typically characterised during uniaxial compression tests via load and deformation measurements. In most practical applications, deformation measurements can only be conducted at the surface of the sample. To understand the influence of this restriction on characterisation results, this study conducts in-situ load tests on hydraulic lime mortar samples with both surface and volumetric imaging, using stereo cameras and synchrotron X-rays. The imaging data are processed with Digital Image and Volume Correlation algorithms (local and global) to obtain full-field displacements and strains. Deformation measurements are then used to conduct surface characterisation with the Virtual Fields Method (VFM) and volumetric characterisation with Finite Element Model Updating (FEMU). Since the inverse models indicate limited identifiability for Poisson’s ratio, only the Young’s moduli are compared. Results indicate that accurate Young’s moduli can be obtained from surface measurements, provided that through-thickness load gradients are considered by averaging VFM results from front and back faces of the sample. In addition, it is shown that a surface characterisation domain away from contacts needs to be chosen to ensure that surface strains are representative of bulk behaviour. Finally, a systematic reduction of elastic moduli with increasing loads is observed, suggesting damage development at relatively low stress levels in hydraulic lime mortars.
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Sep 2026
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