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In this study, anisotropic ductility and associated damage mechanisms of a grade X100 line pipe steel previously studied at the macroscopic scale were investigated using in situ synchrotron radiation computed tomography of notched round bars. Line pipe materials have anisotropic mechanical properties, such as tensile strength, ductility and toughness. Specimens were tested for loading along both rolling (L) and transverse (T) directions. The in situ data collected allowed quantifying both specimen deformation (evolution of the cross section) and microscopic damage parameters such as porosity, void shape and void orientation. Nucleation at small particles ( CaS/TiO 2 ) aligned along the L direction was observed during plastic deformation. It was shown that only very few anisotropic particle clusters are present in the material. However, these clusters led to substantial early void growth for loading normal to the rolling direction, thereby explaining the toughness anisotropy in this material. Significant void growth was observed at the beginning of load decrease for a relatively limited diameter reduction (about 10%). Coalescence of voids within clusters along L direction (Necklace) clearly explained anisotropic rupture. [ABSTRACT FROM AUTHOR]

Quantitative characterization of local strain in silicon wafers is critical in view of issues such as wafer handling during manufacturing and strain engineering. In this work, full-field X-ray microdiffraction imaging using synchrotron radiation is employed to investigate the long-range distribution of strain fields in silicon wafers induced by indents under different conditions in order to simulate wafer fabrication damage. The technique provides a detailed quantitative mapping of strain and defect characterization at the micrometer spatial resolution and holds some advantages over conventional methods. [ABSTRACT FROM AUTHOR]

Abstract: Tomographic imaging using both laboratory sources and synchrotron radiation (SR) was performed to achieve a multi-scale damage assessment of carbon fibre composites subjected to impact damage, allowing various internal damage modes to be studied in three-dimensions. The focus of this study is the comparison of different tomographic methods, identifying their capabilities and limitations, and their use in a complementary manner for creating an overall 3D damage assessment at both macroscopic and microscopic levels. Overall, microfocus laboratory computed tomography (μCT) offers efficient routine assessment of damage at mesoscopic and macroscopic levels in engineering-scale test coupons and relatively high spatial resolutions on trimmed-down samples; whilst synchrotron radiation computed tomography (SRCT) and computed laminography (SRCL) offer scans with the highest image quality, particularly given the short acquisition times, allowing damage micromechanisms to be studied in detail. [Copyright &y& Elsevier]

Synchrotron radiation laminography with X-ray diffraction contrast enables three-dimensional imaging of dislocations in monocrystalline wafers. We outline the principle of the technique, the required experimental conditions, and the reconstruction procedure. The feasibility and the potential of the method are demonstrated by three-dimensional imaging of dislocation loops in an indent-damaged and annealed silicon wafer. [ABSTRACT FROM AUTHOR]

Characterization of the microstructure of thermal barrier coatings (TBCs) is essential for assessing coating lifetime and for understanding the damage mechanisms leading to ceramic layer spallation. Recent progress in synchrotron-radiation computed laminography (SRCL) enables imaging of samples that are thin but extended in two dimensions. This study reports on the first results of the 3-D characterization of electron beam–physical vapour deposition TBCs by SRCL. Image analysis was very helpful in investigating the 3-D microstructure obtained and is also described. [ABSTRACT FROM AUTHOR]

Ductile crack initiation and propagation within a naturally aged aluminium alloy sheet has been observed in situ via synchrotron radiation-computed laminography, a technique specifically adapted to three-dimensional imaging of thin objects that are laterally extended. Voids and intermetallic particles, and their subsequent evolution during ductile crack extension at different associated levels of stress triaxiality, were clearly observed within fracture coupons of a reasonable engineering length-scale, overcoming the conventional sample size limitation of computed tomography at high resolutions. [Copyright &y& Elsevier]

Hard x rays from a synchrotron source are used in this implementation of computed laminography for three-dimensional (3D) imaging of flat, laterally extended objects. Due to outstanding properties of synchrotron light, high spatial resolution down to the micrometer scale can be attained, even for specimens having lateral dimensions of several decimeters. Operating either with a monochromatic or with a white synchrotron beam, the method can be optimized to attain high sensitivity or considerable inspection throughput in synchrotron user and small-batch industrial experiments. The article describes the details of experimental setups, alignment procedures, and the underlying reconstruction principles. Imaging of interconnections in flip-chip and wire-bonded devices illustrates the peculiarities of the method compared to its alternatives and demonstrates the wide application potential for the 3D inspection and quality assessment in microsystem technology. [ABSTRACT FROM AUTHOR]

Synchrotron-radiation tomography was used to investigate early foaming stages of aluminium alloys. Monochromatic radiation, high spatial resolution down to the micrometer scale, partial beam coherence, and holographic reconstruction techniques permit the distinction between different foam constituents which are not visible by other volume imaging techniques. In combination with three-dimensional image analysis, the differences in the pore initiation processes in two different aluminium alloys are shown. We find that, in powder compacts made from prealloyed AA6061 alloy powder, pores appear predominantly around the blowing agent particles whereas, in compacts made from a powder blend of Al and Si, pores tend to initiate around Si particles. [ABSTRACT FROM AUTHOR]

X-ray computed laminography (CL) with synchrotron radiation is used to investigate fracture in carbon fibre–epoxy laminates. CL allows for high-resolution (∼1μm) imaging of laterally extended objects. Whilst artefacts inherent to CL data reduce image quality compared with computed tomography (CT), imaging regions of interest in large planar samples greatly increases the engineering applicability. High-resolution in situ three-dimensional analysis of structural failure is therefore achievable at levels that would be impossible via CT or any other volume-imaging methods. [Copyright &y& Elsevier]

Analysis of the impregnation process during injection experiments in fibre-reinforced polymer composites has been carried out via a three-dimensional in-situ imaging method, namely Synchrotron Radiation Computed Laminography (SR-CL). A resin transfer moulding device was designed to perform injection experiments at different flow rates while, at the same time, the evolution of the flow front was inspected by SR-CL. Injections with flow rates of 50 μ L/min and 300 μ L/min in plain woven E-glass fabrics were carried out, resulting in small capillary number fluid propagation with capillary forces dominant over viscous ones. Intratow and intertow voids were accurately segmented by using a machine learning algorithm that enabled the direct measurement of their time and spatial distribution from the raw XCT volumes. The saturation evolution, void content, shape and spatial distribution quantification are reported. Intratow void formation and transport mechanisms were accurately described, in particular those related with large void splitting including the subsequent flow dragging. Advantages and limitations of the use of SR-CL for the analysis of the impregnation process of dry preforms in liquid moulding are discussed in detail, and in particular, those aspects related with the time acquisition limitations. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The mechanisms behind pore formation in aluminium alloys that are in commercial use for making foam components are still not understood. It is accepted that they play a key role in the quality of the evolving pore structure. In order to shed light on early pore formation, aluminium foams in low expansion stages made by the powder-compact melting process were investigated by synchrotron-based hard X-ray microtomography and quantitative image analysis. The calculated spatial correlation functions between the gas source (TiH2 particles) and the nucleating pores show that the location of pore formation and the spatial gas source distribution for AlSi7 and Al–Si–Cu alloys are essentially independent. Therefore, in the alloys investigated, the position of the melt formation is found to determine the pore nucleation rather than the spatial distribution of TiH2. This behaviour explains the known positive effect on the pore structure achieved by adding copper. [Copyright &y& Elsevier]