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We describe our miniature laser powder bed fusion (L-PBF) system for in situ synchrotron x-ray micro-computed tomography (XCT) at the European Synchrotron Radiation Facility. This replicator was designed to extend the characterization of L-PBF to 3D. This instrument fills in a technical gap because the existing replicators were mostly designed to shed light on the dynamic mechanisms involved in molten pool formation but, therefore, suffered from a lack of 3D information. Technical details regarding the setup and beamline integration are given. Experimental validations via post-mortem XCT scans and in situ scans acquired during experiments conducted at the BM05 beamline of the European Synchrotron Radiation Facility are provided. Based on a few illustrative examples, we show that such a replicator opens the path to collect key 3D information that to date could not be available. Our miniature instrument complements the other replicators developed in the world by other research groups that enable operando x-ray imaging (radiography) and operando x-ray diffraction. [ABSTRACT FROM AUTHOR]

Applying atmospherically plasma-sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective coatings on interconnector steels minimized the chromium-related degradation within solid oxide fuel cell stack-tests successfully. Post-test characterization of the coatings disclosed a severe microstructural and phase evolution. A self-healing of micro-cracks, the formation and agglomeration of small pores, the occurrence of a dense spinel layer at the surface and a strong elemental de-mixing were reported in ex situ experiments. In the present publication, we prove for the first time these mechanisms by tracking the microstructure in situ at a single APS coating using synchrotron X-ray nano-tomography at the European Synchrotron Radiation Facility. Therefore, a 100-µm-long cylindrical sample with a diameter of 123 µm was cut from an APS-MCF free-standing layer and measured within a high-temperature furnace. All microstructural changes mentioned above could be verified. Porosity measurements reveal a decrease in the porosity from 9 to 3% during the annealing, which is in good accordance with the literature. Additionally, a partial detachment of an approximately 5-µm-thick layer at the sample surface is observed. The layer is dense and does not exhibit any cracks which are penetrating the layer. This kind of shell is assumed to be gastight and thus protecting the bulk from further oxidation. [ABSTRACT FROM AUTHOR]

As one of the most important analysis techniques for non-destructive imaging, X-ray tomography has been widely used in materials science, medical science, and industry to evaluate the behavior of porous materials. By using this method, a three dimensional volume can be inspected in order to visualize in situ the progress of damage in materials and this can be analyzed qualitatively and quantitatively. In the present study, we have used X-ray tomography to investigate the fracture behavior of an ERG open cell aluminum foam. The process of damage development of a sample undergoing tension and the relation between the inter-metallics and the cracks can be observed totally by the X-ray tomography set-up. Local tomography has in particular been used to image the microstructure at high resolution. A finite element model has also been developed in order to simulate this process of the damage using the 3D data obtained by the tomography. [ABSTRACT FROM AUTHOR]

Abstract: Recent developments of more powerful synchrotron sources have led to vast improvements in the performance of X-ray imaging. This is manifested by a continuous increase in the impact of synchrotron experiments in many research areas on materials, in particular solidification science. X-ray imaging has been established as a method of choice for in situ and real-time studies of solidification microstructure formation in metallic alloys, with spatio-temporal resolutions at the scales of relevance. In this article, we present illustrative results of the current capabilities of synchrotron X-ray imaging in this field of research, each of them using different X-ray techniques (radiography, topography and tomography). Those results demonstrate the high potential of these techniques for the investigation of dynamical phenomena in materials processing. [Copyright &y& Elsevier]

This article presents the first results of a new experimental technique developed to investigate the evolution of the morphology of the solid and liquid phases during the solidification of a metallic alloy. It consists of ultrafast X-ray microtomography observations of a solidifying aluminum-copper alloy carried out at ESRF. These experiments allow investigating in-situ the formation of the casting microstructure and of the evolution of the morphology of the solid and the liquid phases. It allows also the in-situ determination of the solidification path, of the variation of the copper content in both the liquid and solid phases, and of some other characteristic parameters of the microstructure. Provided that some forthcoming technical improvements on the experimental setup are performed, more quantitative results can be obtained as well as better image quality and resolution. [ABSTRACT FROM AUTHOR]

Abstract: The features associated with modern synchrotron radiation machines (intense and coherent beams) result in a substantial extension of X-ray imaging capabilities in terms of spatial and temporal resolution, phase contrast and 3D images. This allows crystal growth-related information to be obtained which is not available otherwise. After briefly describing the main synchrotron radiation based imaging techniques of interest, we give original examples illustrating the new capabilities for crystal growth: characterisation of crystals grown for applications, such as ice tri-crystals produced for mechanical deformation studies; SiC; crystalline silicon for solar photovoltaic cells; in situ and in real time studies of quasicrystal growth (AlPdMn); and ultrafast tomography for the study of the growth of dendrites in metallic alloys. [Copyright &y& Elsevier]