The joint European Space Agency and Chinese Academy of Sciences Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission will explore global dynamics of the magnetosphere under varying solar wind and interplanetary magnetic field conditions, and simultaneously monitor the auroral response of the Northern Hemisphere ionosphere. Combining these large-scale responses with medium and fine-scale measurements at a variety of cadences by additional ground-based and space-based instruments will enable a much greater scientific impact beyond the original goals of the SMILE mission. Here, we describe current community efforts to prepare for SMILE, and the benefits and context various experiments that have explicitly expressed support for SMILE can of fer. A dedicated group of international scientists representing many different experiment types and geographical locations, the Ground-based and Additional Science Working Group, is facilitating these efforts. Preparations include constructing an online SMILE Data Fusion Facility, the discussion of particular or special modes for experiments such as coherent and incoherent scatter radar, and the consideration of particular observing strategies and spacecraft conjunctions. We anticipate growing interest and community engagement with the SMILE mission, and we welcome novel ideas and insights from the solarterrestrial community.

Abstract Achieving high speed friction stir welding has proven to be challenging for 5xxx-series alloys, as they experience strain hardening during plastic deformation, which is inherent in the FSW process. An earlier publication has discussed the conditions under which welding speeds of up to 1.5 m/min can be achieved in 5182-H111 alloy [1]. The mechanical performance of high speed friction stir welds in 5182-H111 alloy is both surprisingly good and relatively unexplored. Using plates of this alloy welded at a low linear speed of 0.2 m/min as well as at a high speed of 1.5 m/min, the present work evaluated local mechanical properties (microhardness, yield and tensile strength, and fatigue crack growth), in terms of the variation in local microstructure and residual stress. Microstructural variation was investigated via electron back-scatter diffraction (EBSD) and residual stresses were obtained using synchrotron X-ray diffraction strain scanning. The results obtained explain the increased, but different, yield strengths observed in the stir zone and TMAZ regions of the high speed weld and the crack growth rate thresholds.

The EISCAT Scientific Association is currently building the most advanced 3-dimensional imaging radar for atmospheric, ionospheric and near-Earth space investigations. The fully steerable, tri-static, phased-array incoherent scatter radar is located in Skibotn (inland from Tromsø, Norway), Karesuvanto (Finland, north of Kiruna), and Kaiseniemi (Sweden, west of Kiruna). The transmit-receive array at Skibotn consists of about 10,000 aerials and ten 91-aerial outrigger receivers in the immediate vicinity. The receive-only arrays of Kaiseniemi and Karesuvanto consist of about 5,000 aerials each. Construction of the facility began after the project kick-off in September 2017. During 2024, EISCAT_3D will gradually begin operations, starting with a seven-element test system and expanding from that. EISCAT_3D will replace the EISCAT mainland radars, i.e. the mono-static, 930-MHz UHF radar at Tromsø and the tri-static, 224-MHz radar at Tromsø with additional receivers at Sodankylä (Finland) and Kiruna (Sweden). The EISCAT Svalbard Radar (ESR) and the Ionospheric Heating facility at Tromsø will not be affected by EISCAT_3D becoming operational. Here we give an status update of the new facility. EISCAT_3D is a European Strategy Forum for Research Infrastructures (ESFRI) Landmark in the Environment domain.

Fatigue crack initiation in engineering components is predominantly associated with tensile surface residual stresses or stress raisers caused by discontinuities or mechanical notches. During welding, surface residual stresses arising from plastic mismatch due to the temperature gradient can accelerate the initiation of cracks during cyclic fatigue testing. Direct energy surface treatment is currently considered a viable post-processing methodology for modifying surfaces within the weld zone to improve fatigue life. This paper discusses results obtained during experimental research, investigating the effect of direct energy surface treatment on surface residual stresses, microstructure, and fatigue life of cylindrical rotary friction welded Ti-6Al-4 V samples. Direct energy post-processing technique aided in improving the fatigue life of friction welded specimens by modifying the surface microstructure, introducing a uniform refined and homogenous structure in the welded region. This near-surface refined microstructure inhibited crack initiation in the welded region, shifting initiation sites to an area adjacent to the modified surface region.

Electron beam freeform fabrication is a wire feed direct energy deposition additive manufacturing process, where the vacuum condition ensures excellent shielding against the atmosphere and enables processing of highly reactive materials. In this work, this technique is applied for the α + β-titanium alloy Ti-6Al-4V to determine suitable process parameter for robust building. The correlation between dimensions and the dilution of single beads based on selected process parameters, leads to an overlapping distance in the range of 70%–75% of the bead width, resulting in a multi-bead layer with a uniform height and with a linear build-up rate. Moreover, the stacking of layers with different numbers of tracks using an alternating symmetric welding sequence allows the manufacturing of simple structures like walls and blocks. Microscopy investigations reveal that the primary structure consists of epitaxial grown columnar prior β-grains, with some randomly scattered macro and micropores. The developed microstructure consists of a mixture of martensitic and finer α-lamellar structure with a moderate and uniform hardness of 334 HV, an ultimate tensile strength of 953 MPa and rather low fracture elongation of 4.5%. A subsequent stress relief heat treatment leads to a uniform hardness distribution and an extended fracture elongation of 9.5%, with a decrease of the ultimate strength to 881 MPa due to the fine α-lamellar structure produced during the heat treatment. Residual stresses measured by energy dispersive X-ray diffraction shows after deposition 200–450 MPa in tension in the longitudinal direction, while the stresses reach almost zero when the stress relief treatment is carried out.

Ni-base superalloys are critical materials for numerous demanding applications in the energy and aerospace sectors. Their complex chemistry and microstructure require detailed understanding of the operating deformation mechanisms and interaction between the matrix and the hardening phase during plastic deformation. Here we use in-situ neutron diffraction to show that the dependence of the deformation mechanisms and load redistribution on γ′ particle size in a Ni-base superalloy with a γ′ volume fraction of around 20 % can exhibit distinct differences compared to their high volume fraction counterparts. In particular, the load redistribution in the coarse microstructure occurs immediately upon yielding in the present case, whereas high γ′ volume fractions have been observed to initially lead to shear mediated co-deformation before work hardening allows looping to dominate and cause load partitioning at higher stresses. The fine microstructure, on the other hand, behaved similar to high volume fraction alloys, exhibiting co-deformation of the phases due to particle shearing. A recently developed elasto-plastic self-consistent (EPSC) crystal plasticity model, specifically developed for the case of coherent multi-phase materials, could reproduce experimental data with good accuracy. Furthermore, the finite strain formulation of the EPSC model allowed deformation induced texture predictions. The correct trends were predicted by the simulations, but the rate of lattice rotation was slower than experimentally observed. The insights point towards necessary model developments and improvements in order to accurately predict e.g. texture evolution during processing and effect of texture and microstructure on component properties.

Steam turbines used in the power generation industry are subject to fatigue during normal operation which includes transient events such as start-ups and steady state operation. Surface treatment methods, such as shot peening (SP) and roller burnishing, to induce surface compressive residual stresses in critical areas and improve fatigue life are commonly used, but the depth of the induced residual stresses is limited by the process. Laser shock peening (LSP) is a more recent development that has been applied in the aerospace industry on titanium blades, but is not yet commonly used in the power generation industry. The current research is focused on optimizing LSP parameters for the application of the process on 12Cr steels used for turbine blades. Evaluation of the induced residual stress was done with both conventional laboratory Xray diffraction (XRD) and synchrotron X-ray diffraction (SXRD) techniques.

Residual creep ductility of service-aged Cr-Mo-V creep resistant material is considerably lower than that of new material; this affects the long-term creep life performance of components manufactured from such alloys as the creep rate in aged alloy is considerably higher than for new materials. This study focused on the effects of residual stress and post-weld heat treatment (PWHT) on the remaining life of creep-exhausted material after repair welding using nickel-based consumables. Residual stresses attributed to the ferrite-to-austenite phase transformations involve a sudden volume change of the weld material. This can adversely affect aged material, e.g. a 1/2Cr-1/2Mo-1/4V alloy, with low creep ductility and known notch sensitivity rendering this alloy prone to reheat cracking. Coupons prepared from creep damaged Cr-Mo-V pipes (323 mm outside diameter and 36 mm thick) were joined with the tungsten inert gas (TIG) and manual metal arc (MMA) welding processes simulating the original construction joints. Standard welding procedures were used with and without the addition of stress relief and temper post-weld heat treatment. Butt weld coupons were subsequently prepared, using a Ni-based consumable and a conventional ferritic consumable, for tri-axial stress measurements on the SALSA neutron diffraction beamline (ILL Grenoble), d(0) calibration used toothcomb specimens sectioned from the weld coupons. The industrial application of the experiments was sensitivity analysis of residual life prediction in FE modelling of plant system stresses in weld-repaired Cr-Mo-V creep resistant materials.

We report on the measurement of the formation of gamma-ZrH during in situ gaseous charging. The measurements were undertaken using high-energy synchrotron X-ray diffraction. Experimental observation shows that gamma-ZrH can form at 180 degrees C from a mixture of alpha+delta while dehydrogenating at slow cooling rates. The observation is further supported by ex situ laboratory X-ray diffraction on deuterated Zr powder that has undergone a similar heat-treatment cycle. The crystal structure of gamma-ZrH refinement agrees with the reported P4(2)/n structure found in the literature. (C) 2016 Elsevier B.V. All rights reserved.

The physical properties of polycrystalline materials depend on their microstructure, which is the nano- to centimeter scale arrangement of phases and defects in their interior. Such microstructure depends on the shape, crystallographic phase and orientation, and interfacing of the grains constituting the material. This article presents a new non-destructive 3D technique to study centimeter-sized bulk samples with a spatial resolution of hundred micrometers: time-of-flight three-dimensional neutron diffraction (ToF 3DND). Compared to existing analogous X-ray diffraction techniques, ToF 3DND enables studies of samples that can be both larger in size and made of heavier elements. Moreover, ToF 3DND facilitates the use of complicated sample environments. The basic ToF 3DND setup, utilizing an imaging detector with high spatial and temporal resolution, can easily be implemented at a time-of-flight neutron beamline. The technique was developed and tested with data collected at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Complex (J-PARC) for an iron sample. We successfully reconstructed the shape of 108 grains and developed an indexing procedure. The reconstruction algorithms have been validated by reconstructing two stacked Co-Ni-Ga single crystals, and by comparison with a grain map obtained by post-mortem electron backscatter diffraction (EBSD).

Deuteride phases in the zirconium-deuterium system in the temperature range 25-286 degrees C have been studied in-situ by high resolution neutron diffraction. The study primarily focused on observations of delta ->gamma transformation at 180 degrees C, and the peritectoid reaction alpha + delta <-> gamma at 255 degrees C in commetcial grade Zr powder that was deuterated to a deuterium/Zr ratio of one to one. A detailed description of the zirconium deuteride preparation route by high temperature gas loading is also described. The lattice parameters of alpha-Zr, delta-ZrDx and epsilon-ZrDx were determined by whole pattern crystal structure analysis, using Rietveld and Pawley refinements, and are in good agreement with values reported in the literature. The controversial gamma-hydride phase was observed both in-situ and ex-situ in deuterated Zr powder after a heat treatment at 286 degrees C and slow cooling. (C) 2017 Elsevier B.V. All rights reserved.

The effect of cooling rate after solution treatment on the initial structure of concentrated binary Fe-Cr alloys and the effect of the initial structure on phase separation during subsequent aging has been investigated. The nano-scale compositional fluctuations in the bulk of the alloys are studied using small angle neutron scattering and the results are compared with simulations using the Cahn-Hilliard-Cook (CHC) model. The alloys investigated represent different mechanisms of phase separation and at higher Cr content, when spinodal decomposition (SD) is favored, the initial Cr compositional fluctuations due to slow cooling after solution treatment reduce the kinetics of phase decomposition, whereas, at lower Cr composition when nucleation and growth is favored, the kinetics of phase decomposition is more rapid. Regardless of the nominal Cr composition of the alloy, the phase decomposition after extended aging up to 300 h at 748 K is always larger for the more non-random initial structure. The CHC modeling of the cooling process and subsequent initial aging (below 10 h) is in reasonable qualitative agreement with the experimental results for the Fe-40 wt.% Cr alloy decomposing via SD. However, the modeling approach must be refined for accurate quantitative modeling of the full SD process, including coarsening. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The phase evolution in a zirconium-50 deuterium (Zr-50D, at.%) alloy system during thermal cycling has been investigated using in situ high-resolution neutron powder diffraction. The results showed that the peritectoid reaction alpha-Zr + delta-ZrD -> gamma-ZrD previously suggested to occur at high temperatures does not take place in the system. Slow cooling, from high temperatures (>= 520 K) to room temperature at a rate of 5 K min(-1), promoted the gamma-hydride formation rather than fast cooling as reported earlier. In contrast to the observation that the delta-hydride present in the system remained at temperatures up to 740 K, the produced gamma phase transformed to delta-hydride in the temperature range of 370 K-559 K, with the transformation completing at approximately 559 K. It is confirmed that the formation of the gamma-hydride was reproducible with slow cooling, and a diffusion-controlled sluggish delta-to gamma-hydride transformation is suggested to be responsible for the favorable development of gamma-hydride during slow cooling. (C) 2015 Elsevier B.V. All rights reserved.

Application of Sn L-3-XANES to study the oxidation state of alloying additions of tin (1-1.2 wt%) in <2 mu m oxide layers formed on nuclear grade zirconium alloy has been demonstrated. Data obtained for metallic and corroded ZIRLO (TM) (1 wt%Sn) and Zircaloy-4 (1.2 wt% Sn) indicate tin has a similar chemical speciation in both metal alloys but this differs in the oxidised surface layers. By recording XANES at various incident angles to vary the photon penetration depth and amount of the oxide layer probed in the measurement, the authors found evidence that the oxidation of tin progresses with increasing oxide thickness. (C) 2016 The Authors. Published by Elsevier Ltd.

We investigate the formation and dissolution of hydrides in commercially pure zirconium powder in‐situ using high‐energy synchrotron X‐ray radiation. Experimental results showed a continuous phase transition between the δ and ε zirconium hydride phases with indication of a second order phase transformation.

Self-assembly due to phase separation within a miscibility gap is important in numerous material systems and applications. A system of particular interest is the binary alloy system Fe-Cr, since it is both a suitable model material and the base system for the stainless steel alloy category, suffering from low-temperature embrittlement due to phase separation. Structural characterization of the minute nano-scale concentration fluctuations during early phase separation has for a long time been considered a major challenge within material characterization. However, recent developments present new opportunities in this field. Here, we present an overview of the current capabilities and limitations of different techniques. A set of Fe-Cr alloys were investigated using small-angle neutron scattering (SANS), atom probe tomography, and analytical transmission electron microscopy. The complementarity of the characterization techniques is clear, and combinatorial studies can provide complete quantitative structure information during phase separation in Fe-Cr alloys. Furthermore, we argue that SANS provides a unique in-situ access to the nanostructure, and that direct comparisons between SANS and phase-field modeling, solving the non-linear Cahn Hilliard equation with proper physical input, should be pursued.

Two complementary experimental techniques have been used to study the evolution of crack-tip strain fields in a thin (plane stress dominated) compact tension sample following a single overload (OL) event. The total strain has been characterised at the surface by digital image correlation (DIC), while the elastic strain field in the bulk (interior) behaviour has been characterised by means of synchrotron X-ray diffraction (XRD). Surface and bulk information allowed us to visualise the evolution of the strain fields before the OL event, during the OL event, just after it and at various stages after it. Unlike previous work, complete 2D maps of elastic strains around the crack-tip were acquired at 60 mu m spatial resolution by XRD. The strain data were used to estimate the effective crack driving force at the surface and at the mid plane. The DIC shows less crack opening displacement after overload and the XRD a lower crack-tip peak stress after OL until the crack has grown past the compressive crack-tip residual stress after which the behaviour returned to that for the baseline fatigue response. While the compressive residual stress introduced by the OL offsets the crack-tip stress field as it grows through the overload plastic zone, the changes in crack-tip stress over each cycle are the same before and at all stages after OL.