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Abstract: The plumes of Enceladus contain a non-ice component that originates from aqueous processes occurring within the interior 1,2. The ocean of Enceladus is thought to be connected to the surface across a range of time scales. These processes range from the rapid eruption of cryovolcanic plumes to slow crustal convection on geological timescales3,4. In every case, the system will have a temperature and geochemical evolution as it freezes, with the history of evolution recorded in the sequence of mineral precipitation. Analogously to igneous and metamorphic petrology, we can explore the mineralogy and its context to reconstruct the history of that sample. Most importantly, for astrobiological investigations, the formation and cryo-petrological study of inorganic salts can be used to identify sites of recent exposure on the surface. Synchrotron X-ray techniques allow fast, high-resolution probing of these systems with X-ray light. By exploring large, multi-component samples with multiple techniques, with variable temperature over time we can reveal many emergent processes that may not be predictable with simple phase diagrams. We use a combination of synchrotron powder X-ray diffraction (PXRD) and X-ray microtomography (µCT) across multiple beamlines at Diamond Light Source (I11, I12 and DIAD). Using a multi-modal approach, we present an in-situ study of the low-temperature phase behaviour of Na-Cl-HCO3 fluids. We employ K11-DIAD (Dual Imaging and Diffraction) to carry out ‘image-guided diffraction’ on an Enceladus-type sample frozen in real-time. DIAD’s unique capabilities allow us not only to study microstructure down to 1 µm but also to carry out spatially resolved XRD and identify solid phases present. We present, for the first time, the use of dual imaging and diffraction of a Na-Cl-CO₃ solution frozen in real time in 3 dimensions [Figure 1]. DIAD’s imaged guided diffraction provides spatially-resolved XRD, allowing us to probe different regions of our sample and identify the formation of Na2CO₃ hydrates. We show the influence of carbonate chemistry on the sequence of cryogenic precipitation and the development of complex microstructures. These results provide insights into crustal transport processes and will help with interpreting observational data from upcoming Galilean missions.

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Abstract: We use in situ synchrotron X-ray diffraction measurements to monitor the solvothermal crystallization mechanism of the aperiodic metal–organic framework TRUMOF-1. Following an initial incubation period, TRUMOF-1 forms as a metastable intermediate that subsequently transforms into an ordered product with triclinic crystal symmetry. We determine the structure of this ordered phase, which we call msw-TRUMOF-1, and show that it is related to TRUMOF-1 through topotactic reorganization of linker occupancies. Our results imply that the connectivity of TRUMOF-1 can be reorganized, as required for data storage and manipulation applications.

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Abstract: 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.

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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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Abstract: Transitions in eruptive style during volcanic eruptions strongly depend on how easily gas and magma decouple during ascent. Stronger gas-melt coupling favors highly explosive eruptions, whereas weaker coupling promotes lava fountaining and lava flows. The mechanisms producing these transitions are still poorly understood because of a lack of direct observations of bubble dynamics under natural magmatic conditions. Here, we combine x-ray radiography with a novel high-pressure/high-temperature apparatus to observe and quantify in real-time bubble growth and coalescence in basaltic magmas from 100 megapascals to surface. For low-viscosity magmas, bubbles coalesce and recover a spherical shape within 3 seconds, implying that, for lava fountaining activity, gas and melt remain coupled during the ascent up to the last hundred meters of the conduit. For higher-viscosity magmas, recovery times become longer, promoting connected bubble pathways. This apparatus opens frontiers in unraveling magmatic/volcanic processes, leading to improved hazard assessment and risk mitigation.