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Lightweight design strategies and advanced energy applications call for high-strength Al alloys that can serve in the 300‒400 °C temperature range. However, the present commercial high-strength Al alloys are limited to low-temperature applications of less than ~150 °C, because it is challenging to achieve coherent nanoprecipitates with both high thermal stability (preferentially associated with slow-diffusing solutes) and large volume fraction (mostly derived from high-solubility and fast-diffusing solutes). Here we demonstrate an interstitial solute stabilizing strategy to produce high-density, highly stable coherent nanoprecipitates (termed the V phase) in Sc-added Al–Cu–Mg–Ag alloys, enabling the Al alloys to reach an unprecedented creep resistance as well as exceptional tensile strength (~100 MPa) at 400 °C. The formation of the V phase, assembling slow-diffusing Sc and fast-diffusing Cu atoms, is triggered by coherent ledge-aided in situ phase transformation, with diffusion-dominated Sc uptake and self-organization into the interstitial ordering of early-precipitated Ω phase. We envisage that the ledge-mediated interaction between slow- and fast-diffusing atoms may pave the way for the stabilization of coherent nanoprecipitates towards advanced 400 °C-level light alloys, which could be readily adapted to large-scale industrial production.High-density, highly stable coherent nanoprecipitates are created in Al alloys that enable high strength and creep resistance at 400 °C. This is realized via a growth-ledge-triggered in situ phase transformation assembling slow-diffusing solutes with high-solubility solutes into nanoprecipitates.

The application of wide field-of-view detection systems to atom probe experiments emphasizes the importance of careful parameter selection in the tomographic reconstruction of the analyzed volume, as the sensitivity to errors rises steeply with increases in analysis dimensions. In this article, a self-consistent method is presented for the systematic determination of the main reconstruction parameters. In the proposed approach, the compression factor and the field factor are determined using geometrical projections from the desorption images. A three-dimensional Fourier transform is then applied to a series of reconstructions, and after comparing to the known material crystallography, the efficiency of the detector is estimated. The final results demonstrate a significant improvement in the accuracy of the reconstructed volumes.

Atom probe tomography (APT) is often introduced as providing “atomic-scale” mapping of the composition of materials and as such is often exploited to analyze atomic neighborhoods within a material. Yet quantifying the actual spatial performance of the technique in a general case remains challenging, as it depends on the material system being investigated as well as on the specimen's geometry. Here, by using comparisons with field-ion microscopy experiments, field-ion imaging and field evaporation simulations, we provide the basis for a critical reflection on the spatial performance of APT in the analysis of pure metals, low alloyed systems and concentrated solid solutions (i.e., akin to high-entropy alloys). The spatial resolution imposes strong limitations on the possible interpretation of measured atomic neighborhoods, and directional neighborhood analyses restricted to the depth are expected to be more robust. We hope this work gets the community to reflect on its practices, in the same way, it got us to reflect on our work.

Quantitatively characterizing precipitate microstructures in metals by small-angle scattering poses specific challenges as compared to other areas of application of this technique. In terms of size and morphology evaluation, these include the presence of a significant size distribution, non-isotropic shapes, and interpretation complicated by a partial averaging due to a non-random texture. In terms of volume fraction evaluation, these include the imperfect knowledge of the chemical composition of very small objects. This paper, based on a presentation given at the “Neutron and X-Ray Studies of Advanced Materials V: Centennial” symposium of the 2012 TMS conference, reviews the strategies that can be applied in different characteristic cases to obtain a robust quantification of precipitate microstructures.

Material sustainability requires energy‐efficient and rapid strengthening processes. In alloys, strengthening through diffusion‐driven precipitation is limited by the low vacancy concentration, with fewer than one vacancy per 100 billion lattice sites at room temperature in metals such as aluminum and iron under thermodynamic equilibrium. Artificially increasing vacancy concentrations by 1 to 7 orders of magnitude above equilibrium levels through quenching, irradiation, or deformation can significantly accelerate material strengthening. However, measuring vacancy concentrations below 10−7 in alloys and achieving spatial mapping remain challenging. Here, a vacancy‐mediated gradient microstructure near grain boundaries is reported and analyzed to investigate diffusion enhancement and the local vacancy population in an Al‐Zn system. This method uses cryogenic processes to preserve excess vacancies and halt microstructure evolution, enabling intermittent measurement of compositional fluctuations during ultrafast spinodal decomposition. It allows for the assessment of diffusion enhancement and determination of vacancy supersaturation in sub‐micrometer regions. Liquid nitrogen–quenched Al–12.5 at.% Zn alloy shows a vacancy concentration of ≈10−7 at room temperature, dropping to 10−9 after 3 h, with significant spatial variation near grain boundaries. This work addresses gaps in understanding the evolution and distribution of vacancies across various measurement scales, advancing the control of vacancies to enhance the strengthening of engineering alloys. Combining cryogenic sample preparation and intermittent atom probe tomography analyses enables the tracking of excess vacancy concentrations in as‐quenched Al‐Zn alloys. This approach reveals a vacancy‐mediated gradient spinodal decomposition microstructure near grain boundaries, with the ability to measure vacancy concentrations below 10−7. This study clarifies the spatial evolution of vacancies, advancing the control of vacancies to enhance the strengthening of materials.

The ability to non-destructively measure the structural properties of devices, either in situ or operando, are now possible using an intense X-ray synchrotron source combined with specialized equipment. This tool attracted researchers, in particular metallurgists, to attempt more complex and ambitious experiments aimed at answering unresolved questions in formation mechanisms, phase transitions, and magnetism complex alloys for industrial applications. In this paper, we introduce the diffraction diffusion anomale multi-longueur d’onde (D2AM) beamline, a French collaborating research group (CRG) beamline at the European Synchrotron Radiation Facility (ESRF), partially dedicated to in situ X-ray scattering experiments. The design of the beamline combined with the available equipment (two-dimensional fast photon counting detectors, sophisticated high precision kappa diffractometer, a variety of sample environments, continuous scanning for X-ray imaging, and specific software for data analysis) has made the D2AM beamline a highly efficient tool for advanced, in situ synchrotron characterization in materials science, e.g., single crystal or polycrystalline materials, powders, liquids, thin films, or epitaxial nanostructures. This paper gathers the main elements and equipment available at the beamline and shows its potential and flexibility in performing a wide variety of temporally, spatially, and energetically resolved X-ray synchrotron scattering measurements in situ.

This paper presents an experimental and modeling study of the mechanical behavior of an electron beam welded EN-AW 7020 aluminum alloy. The heterogeneous distribution of mechanical properties is characterized by micro-tensile tests and by strain field measurements using digital image correlation technic. These results are related to the microstructural observation presented in the companion paper. The mechanical behavior of the weld is simulated by a finite element model including a Gurson-type damage evolution model for void evolution. The model is shown to be capable of describing accurately experimental situations where the sample geometry is varied, resulting in stress triaxiality ratios ranging from 0.45 to 1.3.

This work presents a detailed, multiscale, spatially resolved study of the microstructure of an electron beam butt weld of the EN-AW 7020 (Al-Zn-Mg) alloy. Using a combination of optical, scanning and transmission electron microscopy, differential scanning calorimetry, and small-angle X-ray scattering, the distribution of phases in the different areas of the heat-affected zone and of the fusion zone is quantitatively characterized, for two different aging states: naturally aged after welding and artificially aged at 423 K (150 °C). The heat-affected zone consists of regions experiencing different levels of precipitate dissolution and coarsening during welding as well as new precipitation during post-welding heat treatment (PWHT). The microstructure of the fusion zone is typical from a fast solidification process, with a strong solute segregation in the interdendritic zones. The precipitate distribution after PWHT follows this solute distribution, and the resulting hardness is much lower than the relatively homogeneous value in the base metal and the heat-affected zone.

High strength Al-alloys are highly susceptible to intergranular embrittlement, which severely limits their lifetime. This article summarizes our recent work on the effect of solute segregation in the precipitation behavior at grain boundaries (GBs) compared to the grain interiors. Solute segregation could accelerate the precipitation behavior at GBs, which causes the formation of coarse precipitates and precipitate free zones along GBs. Furthermore, the interplay of solute segregation and the local structure at GBs has been considered. We show that the distinct segregation and precipitation behavior occurs within the same GB, which makes the GB excess of solutes at one facet significantly higher than the other facet. This paper enriches the current understanding on the role of chemistry and structure at GBs related to intergranular fracture and corrosion resistance in high strength Al-alloys.

This study allowed to understand the influence of severe plastic deformation by High Pressure Torsion (HPT) on an Al-Zn-Mg-Cu alloy and more especially the influence on precipitation mechanisms thanks to the correlation between DSC, SAXS and STEM data. A shear strain of γ ≈ 200 was first applied to the alloy. This deformation leads to nanostructuration, creation of high density of defects but also solute segregation to boundaries and dynamic precipitation. These specific microstructural features give rise to an acceleration of precipitation kinetics during heat treatments but also to a lower precipitation temperature and a modification of final precipitates size distribution as compared to the un-deformed alloy.