The elastic properties of amorphous TiNiSn, a promising half-Heusler system for flexible and wearable devices, were investigated using experimental and theoretical methods. Nanoindentation measurements performed on amorphous TiNiSn thin film grown by magnetron sputtering yielded an elastic (Young's) modulus value of 132 GPa. To corroborate this result, density functional theory (DFT) calculations and two machine learning models were employed, where the latter were trained on available literature data. The DFT-derived elastic modulus of amorphous TiNiSn is 113 GPa (stress-free conditions), which is 15% lower than the experimental value. However, when hydrostatic stress is considered, arising from possible thermal loads and ion bombardment during thin film synthesis, the difference is reduced to 5%. Electronic structure analysis reveals that amorphous TiNiSn exhibits predominantly covalent bonding with a minor metallic contribution, which is consistent with the measured elastic modulus. Although both machine learning models underestimate the experimental modulus more than DFT, the theoretical results enhance understanding of the elastic behaviour of amorphous TiNiSn and highlight its potential for future applications in flexible microelectronic systems.

High-resolution synchrotron X-ray tomography combined with digital volume correlation (DVC) enables characterization of three-dimensional strain fields. When local tomography is used to investigate specimens larger than the field of view (FOV), the resulting subvolumes must be stitched together to form a single volume, thereby introducing strain uncertainties in DVC analyses. The present work quantifies such strain uncertainties obtained from extended-FOV synchrotron X-ray tomography of an Al99.5 metal matrix syntactic foam. To achieve this, zero-strain repeated scans were performed on the specimen. Two local DVC strategies, regular-grid DVC and discrete DVC, were applied to the stitched volumes to quantify the spatial distribution and magnitude of strain uncertainties. Both approaches confirm a consistent spatial hierarchy of strain uncertainties. Non-overlapping regions exhibit uncertainties of approximately 0.06%, while overlapping regions show uncertainties of approximately 0.17% (Frobenius norm of the Green-Lagrangian strain tensor). The spatial distribution of strain uncertainty in the stitched volume indicates that uncertainties in overlapping regions are two to four times higher compared to non-overlapping regions. The zero-strain stitching uncertainty quantification method demonstrated here is recommended as a standard pre-characterization step for any DVC study involving stitched tomographic volumes.

Brazed stainless steel joints are critical in heat exchanger applications but often suffer from residual stresses and brittle intermetallics. Using in-situ synchrotron X-ray diffraction and fluorescence at the DanMAX beamline, we investigated Fe-based filler joints in SS316 under tensile loading. Elemental mapping and phase analysis revealed distinct interfacial solidification zones (ISZ), athermal solidification zones (ASZ), and diffusion-affected zones (DAZ). Relative to the base composition, the ISZ showed an average Ni enrichment of ∼35%, while the ASZ exhibited localized Mo and Cr enrichment of up to ∼40% and ∼10%, respectively. The diffusion affected zone was strongly asymmetric, spanning approximately 400μm on one side of the ∼250μm wide joint and approximately 200μm on the other. Strain tensor mapping showed strong elastic anisotropy and stress localization at boride-rich zones, correlating with the observed fracture path. The results demonstrate the capability of synchrotron-based analysis to provide comprehensive insight into the interplay between chemical composition, microstructure, and stress in governing joint integrity, thereby informing strategies for improving toughness through process optimization.

Growth of the intermetallic compound (IMC) Cu₆Sn₅ in Sn/Cu coatings is a major source of stress evolution and is closely linked to the reliability of electroplated Sn layers, including their susceptibility to whisker formation. Here, we investigate how Sn grain morphology and grain boundary (GB) transport control stress development during diffusion-controlled Cu₆Sn₅ growth. A thermodynamically consistent sharp-interface framework is developed that couples atomic diffusion, elasto-plastic deformation, moving interphase interfaces and GB diffusion and sliding. The model is solved in a finite element setting using the Voronoi implicit interface method to capture evolving Cu₆Sn₅ morphologies. Simulations of Sn coatings on Cu substrates reproduce experimentally observed trends in Cu6Sn5 growth and biaxial stress evolution. In columnar Sn microstructures, IMC growth produces a build-up of biaxial compressive stress that saturates at experimentally relevant levels, even without GB creep. In contrast, non-columnar microstructures activate GB diffusion and sliding along inclined boundaries, leading to substantial stress relaxation. The results show that GB diffusion and sliding are orientation-dependent relaxation mechanisms rather than sources of stress generation, providing a mechanistic explanation for the reduced stress levels observed in non-columnar Sn coatings.

The Ni-based superalloy Haynes 282 exhibits rapid γ′ precipitation kinetics, and experimental studies have shown the formation of in-process precipitates in samples produced using the direct energy deposition additive manufacturing method, laser metal deposition (LMD). Understanding how these precipitates form and influence the final microstructure is essential for predicting and controlling the mechanical properties of processed Haynes 282. In this study, the particle size and volume fraction of γ′ precipitates formed in LMD samples are simulated using classical nucleation and growth theory (CNGT). To account for the thermal history during manufacturing, the precipitate model is implemented as a multi-scale framework integrated into a finite element software. Calphad thermodynamic and diffusion data descriptions are used as input to the CNGT model to simulate the precipitation kinetics during different heat treatments. The simulated results are compared with experimental data obtained from small- and wide-angle X-ray scattering, as well as from atom probe tomography. The simulations show good agreement with experimental findings, demonstrating that thermodynamic databases can be used to accurately simulate precipitate evolution in LMD-processed Haynes 282 using CNGT.

In this work we introduce the concept of natural ageing via precipitation arising from eutectic cell structure (PEC-ageing). Natural age-strengthening in grey cast iron at room temperature is long recognised yet still poorly understood, despite its beneficial effect on tensile strength and machinability. We investigate its un derlying mechanisms by comparing fresh and naturally aged industrial grey cast iron using high-resolution synchrotron Wide-Angle X-ray Scattering (WAXS), complemented by scanning electron microscopy and X-ray energy-dispersive spectroscopy. A strict sample-preparation process was designed to minimize artificial ageing and X-ray attenuation artefacts. We present direct experimental evidence of an X-ray diffraction peak that forms upon natural ageing in grey cast iron. Based on its position in reciprocal space, a plausible candidate for this peak is the iron nitride phase Fe4N. Spatially resolved analysis further shows that this phase is strongly localised along eutectic cell boundaries, supporting a nitride-related, boundary-mediated precipitation mechanism (PEC-ageing) as the main driver of the ageing phenomenon. These results provide a spatially resolved description of natural ageing in grey cast iron, establish WAXS as a powerful tool to track ageing-related changes in the bulk, and highlight that logistics and sample preparation remain the main practical challenges for future in-situ studies.

In complex stress environments, good mechanical flexibility and stretchability can help an alloy retain its properties. While literature has focused on flexibility and thermal stability of amorphous TiNiSn, less attention has been paid to its stress-induced devitrification, which may lead to embrittlement. In this work, amorphous TiNiSn thin films with various Sn content were synthesized on flexible substrates using direct current magnetron sputtering. The effects of stress, temperature, composition, and annealing time were explored by subjecting the samples to gradually increasing tensile loads at temperatures between ambient and 350 °C. The short and medium-range order were investigated using pair distribution functions extracted from synchrotron radiation X-ray diffraction data. The influence of stress up to 3.2 GPa at temperature of 250 °C and below on the structure of the amorphous TiNiSn thin films is negligible. For stoichiometric TiNiSn at 300 °C, stress-induced devitrification occurs above a tensile load of 1.0 GPa. The Sn-poor samples require less stress to devitrify than the Sn-rich compositions. Stress-induced crystallization may provide a convenient way of inducing growth of nanocrystals within an amorphous matrix, promoting development of crystalline-amorphous composites.

The aim of this study is to explore the internal damage mechanisms of AlSi12 metal matrix syntactic foam (MMSF) with embedded ceramic hollow spheres (CHSs) to understand the damage behavior during compressive loading. To achieve this goal, in situ synchrotron X-ray tomography is used. A qualitative and quantitative assessment of the initiation and gradual collapse of matrix, filler material, and pores is presented. The imaging-based investigation provided detailed visualization and tracking of failure mechanisms of the MMSF, with emphasis on the collapse of hollow spheres at the microstructural level. The structural parameters describing performance limits are experimentally determined and correlated with internal mechanisms. It is concluded that a homogeneous distribution of the second-phase filler material results in a sequential collapse in a localized region; this leads to controlled and predictable energy absorption. The CHSs rupture is found to be location dependent within the localized shear band region, with spheres of all diameters failing to a similar extent. The results from this work can be used to train or validate predictive models of MMSFs deformed under compressive loading conditions by correlating the 3D damage progression with the overall mechanical response.

The evolution of the microstructure in 316L stainless steel foams with three different degrees of porosity during compression was studied in situ using the combination of synchrotron X-ray tomography and diffraction line profile analysis. The former and the latter techniques were applied for the investigation of the change of the porosity and the defect structure in the walls, respectively. The stress-strain curves of the foams up to a compressive strain of 0.6 can be divided into three stages irrespectively of the degree of porosity. In the first and third stages, hardening was observed while in the intermediate second stage, a stress drop occurred due to cracking. The evolution of the dislocation density in the walls was similar for all initial porosities: it increased from (2–3) × 1014 m−2 to (14–17) × 1014 m−2. The relationship between relative stress and relative density can not be described with traditional models, since the walls consist of spherical particles in the present foams while the former models assumed that the walls comprise rods of equal cross-section. It was revealed that in the first stage of compression (up to the strain of 0.2–0.25) the wall hardening due to the increase of the dislocation density gave similar or higher contribution to increase of the flow stress than that caused by the reduction of porosity due to densification.

This paper presents a general level set framework for modelling diffusive solid-state phase transformation processes in binary systems comprising several grains and phases. Notably, it is demonstrated how the Voronoi implicit interface method (VIIM) can be used to simulate microstructure evolution in polycrystals driven by diffusion. The key advantage of VIIM is that a single level set function can be utilized to describe the evolution of the microstructure. Thus, the computational cost is significantly reduced compared to more traditional approaches, in which each grain in the microstructure is assigned a separate level set function. Moreover, VIIM facilitates the reconstruction of a fully compatible grain boundary network without the presence of any void regions or grain overlaps. The reconstruction procedure does not require any special handling of junctions and can be easily extended to higher dimensions. Moreover, the reconstruction step enables an adaptive remeshing technique to be employed such that the mesh nodes conform with the location of the grain boundaries. Hence, the diffusion problem can be solved in distinct phase domains, demarcated by sharp interfaces. The kinetics of the phase interfaces are described by the amount of flux towards the interface in accordance with the theory of diffusion-controlled phase transformations. To examine the capabilities of the proposed model, both single-phase and multiphase problems are examined. For the single-phase problem, it is shown that the model behaves in accordance with analytical solutions and maintains mass conservation. For the multiphase problems, two model cases of polycrystals that share the same initial geometry but exhibit different phase distributions are investigated, as well as a representative microstructure example. The evolution of the microstructures towards an equilibrium state is in agreement with the expected phase fractions and demonstrates that the model produces reliable results. The error in mass conservation of the considered multiphase examples is within a margin of +/- 5%.