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15 pages, 3475 KiB

Open AccessArticle

Role of Hydrogen-Charging on Nucleation and Growth of Ductile Damage in Austenitic Stainless Steels

by Eric Maire, Stanislas Grabon, Jérôme Adrien, Pablo Lorenzino, Yuki Asanuma, Osamu Takakuwa and Hisao Matsunaga

Materials 2019, 12(9), 1426; https://doi.org/10.3390/ma12091426 - 1 May 2019

Cited by 12 | Viewed by 5052

Abstract

Hydrogen energy is a possible solution for storage in the future. The resistance of packaging materials such as stainless steels has to be guaranteed for a possible use of these materials as containers for highly pressurized hydrogen. The effect of hydrogen charging on [...] Read more.

Hydrogen energy is a possible solution for storage in the future. The resistance of packaging materials such as stainless steels has to be guaranteed for a possible use of these materials as containers for highly pressurized hydrogen. The effect of hydrogen charging on the nucleation and growth of microdamage in two different austenitic stainless steels AISI316 and AISI316L was studied using in situ tensile tests in synchrotron X-ray tomography. Information about damage nucleation, void growth and void shape were obtained. AISI316 was found to be more sensitive to hydrogen compared to AISI316L in terms of ductility loss. It was measured that void nucleation and growth are not affected by hydrogen charging. The effect of hydrogen was however found to change the morphology of nucleated voids from spherical cavities to micro-cracks being oriented perpendicular to the tensile axis. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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22 pages, 14208 KiB

Open AccessArticle

Variation of the Pore Morphology during the Early Age in Plain and Fiber-Reinforced High-Performance Concrete under Moisture-Saturated Curing

by Miguel A. Vicente, Jesús Mínguez and Dorys C. González

Materials 2019, 12(6), 975; https://doi.org/10.3390/ma12060975 - 24 Mar 2019

Cited by 7 | Viewed by 3598

Abstract

In this paper, two concrete mixtures of plain concrete (PC) and steel fiber-reinforced high-performance concrete (SFRC) have been scanned in order to analyze the variation of the pore morphology during the first curing week. Six cylinders of 45.2-mm diameter 50-mm height were performed. [...] Read more.

In this paper, two concrete mixtures of plain concrete (PC) and steel fiber-reinforced high-performance concrete (SFRC) have been scanned in order to analyze the variation of the pore morphology during the first curing week. Six cylinders of 45.2-mm diameter 50-mm height were performed. All of the specimens were kept in a curing room at 20 °C and 100% humidity. A computed tomography (CT) scan was used to observe the internal voids of the mixtures, and the data were analyzed using digital image processing (DIP) software, which identified and isolated each individual void in addition to extracting all of their geometrical parameters. The results revealed that the SFRC specimens showed a greater porosity than the PC ones. Moreover, the porosity increased over time in the case of SFRC, while it remained almost constant in the case of PC. The porosity increased with the depth in all cases, and the lowest porosity was observed in the upper layer of the specimens, which is the one that was in contact with the air. The analysis of the results showed that the fibers provided additional stiffness to the cement paste, which was especially noticeable during this first curing week, resulting in an increasing of the volume of the voids and the pore size, as well as a reduction in the shape factor of the voids, among other effects. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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15 pages, 44822 KiB

Open AccessFeature PaperArticle

3D Analysis of Deformation and Porosity of Dry Natural Snow during Compaction

by Lavan Kumar Eppanapelli, Fredrik Forsberg, Johan Casselgren and Henrik Lycksam

Materials 2019, 12(6), 850; https://doi.org/10.3390/ma12060850 - 13 Mar 2019

Cited by 8 | Viewed by 3843

Abstract

The present study focuses on three-dimensional (3D) microstructure analysis of dry natural snow during compaction. An X-ray computed microtomography (micro-CT) system was used to record a total of 1601 projections of a snow volume. Experiments were performed in-situ at four load states as [...] Read more.

The present study focuses on three-dimensional (3D) microstructure analysis of dry natural snow during compaction. An X-ray computed microtomography (micro-CT) system was used to record a total of 1601 projections of a snow volume. Experiments were performed in-situ at four load states as 0 MPa, 0.3 MPa, 0.6 MPa and 0.8 MPa, to investigate the effect of compaction on structural features of snow grains. The micro-CT system produces high resolution images (4.3 μm voxel) in 6 h of scanning time. The micro-CT images of the investigated snow volume illustrate that grain shapes are mostly dominated by needles, capped columns and dendrites. It was found that a significant number of grains appeared to have a deep hollow core irrespective of the grain shape. Digital volume correlation (DVC) was applied to investigate displacement and strain fields in the snow volume due to the compaction. Results from the DVC analysis show that grains close to the moving punch experience most of the displacement. The reconstructed snow volume is segmented into several cylinders via horizontal cross-sectioning, to evaluate the vertical heterogeneity of porosity distribution of the snow volume. It was observed that the porosity (for the whole volume) in principle decreases as the level of compaction increases. A distinct vertical heterogeneity is observed in porosity distribution in response to compaction. The observations from this initial study may be useful to understand the snow microstructure under applied stress. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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13 pages, 44562 KiB

Open AccessArticle

3D Imaging of Indentation Damage in Bone

by Tristan Lowe, Egemen Avcu, Etienne Bousser, William Sellers and Philip J. Withers

Materials 2018, 11(12), 2533; https://doi.org/10.3390/ma11122533 - 13 Dec 2018

Cited by 5 | Viewed by 5506

Abstract

Bone is a complex material comprising high stiffness, but brittle, crystalline bio-apatite combined with compliant, but tough, collagen fibres. It can accommodate significant deformation, and the bone microstructure inhibits crack propagation such that micro-cracks can be quickly repaired. Catastrophic failure (bone fracture) is [...] Read more.

Bone is a complex material comprising high stiffness, but brittle, crystalline bio-apatite combined with compliant, but tough, collagen fibres. It can accommodate significant deformation, and the bone microstructure inhibits crack propagation such that micro-cracks can be quickly repaired. Catastrophic failure (bone fracture) is a major cause of morbidity, particularly in aging populations, either through a succession of small fractures or because a traumatic event is sufficiently large to overcome the individual crack blunting/shielding mechanisms. Indentation methods provide a convenient way of characterising the mechanical properties of bone. It is important to be able to visualise the interactions between the bone microstructure and the damage events in three dimensions (3D) to better understand the nature of the damage processes that occur in bone and the relevance of indentation tests in evaluating bone resilience and strength. For the first time, time-lapse laboratory X-ray computed tomography (CT) has been used to establish a time-evolving picture of bone deformation/plasticity and cracking. The sites of both crack initiation and termination as well as the interconnectivity of cracks and pores have been visualised and identified in 2D and 3D. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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12 pages, 6929 KiB

Open AccessArticle

Investigation of the Foam Development Stages by Non-Destructive Testing Technology Using the Freeze Foaming Process

by Johanna Maier, Thomas Behnisch, Vinzenz Geske, Matthias Ahlhelm, David Werner, Tassilo Moritz, Alexander Michaelis and Maik Gude

Materials 2018, 11(12), 2478; https://doi.org/10.3390/ma11122478 - 6 Dec 2018

Cited by 2 | Viewed by 3372

Abstract

With a novel Freeze Foaming method, it is possible to manufacture porous cellular components whose structure and composition also enables them for application as artificial bones, among others. To tune the foam properties to our needs, we have to understand the principles of [...] Read more.

With a novel Freeze Foaming method, it is possible to manufacture porous cellular components whose structure and composition also enables them for application as artificial bones, among others. To tune the foam properties to our needs, we have to understand the principles of the foaming process and how the relevant process parameters and the foam’s structure are linked. Using in situ analysis methods, like X-ray microcomputed tomography (µCT), the foam structure and its development can be observed and correlated to its properties. For this purpose, a device was designed at the Institute of Lightweight Engineering and Polymer Technology (ILK). Due to varying suspension temperature and the rate of pressure decrease it was possible to analyze the foam’s developmental stages for the first time. After successfully identifying the mechanism of foam creation and cell structure formation, process routes for tailored foams can be developed in future. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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11 pages, 6176 KiB

Open AccessArticle

Time-Lapse Helical X-ray Computed Tomography (CT) Study of Tensile Fatigue Damage Formation in Composites for Wind Turbine Blades

by Ying Wang, Lars P. Mikkelsen, Grzegorz Pyka and Philip J. Withers

Materials 2018, 11(11), 2340; https://doi.org/10.3390/ma11112340 - 21 Nov 2018

Cited by 18 | Viewed by 5269

Abstract

Understanding the fatigue damage mechanisms in composite materials is of great importance in the wind turbine industry because of the very large number of loading cycles rotor blades undergo during their service life. In this paper, the fatigue damage mechanisms of a non-crimp [...] Read more.

Understanding the fatigue damage mechanisms in composite materials is of great importance in the wind turbine industry because of the very large number of loading cycles rotor blades undergo during their service life. In this paper, the fatigue damage mechanisms of a non-crimp unidirectional (UD) glass fibre reinforced polymer (GFRP) used in wind turbine blades are characterised by time-lapse ex-situ helical X-ray computed tomography (CT) at different stages through its fatigue life. Our observations validate the hypothesis that off-axis cracking in secondary oriented fibre bundles, the so-called backing bundles, are directly related to fibre fractures in the UD bundles. Using helical X-ray CT we are able to follow the fatigue damage evolution in the composite over a length of 20 mm in the UD fibre direction using a voxel size of (2.75 µm)³. A staining approach was used to enhance the detectability of the narrow off-axis matrix and interface cracks, partly closed fibre fractures and thin longitudinal splits. Instead of being evenly distributed, fibre fractures in the UD bundles nucleate and propagate locally where backing bundles cross-over, or where stitching threads cross-over. In addition, UD fibre fractures can also be initiated by the presence of extensive debonding and longitudinal splitting, which were found to develop from debonding of the stitching threads near surface. The splits lower the lateral constraint of the originally closely packed UD fibres, which could potentially make the composite susceptible to compressive loads as well as the environment in service. The results here indicate that further research into the better design of the positioning of stitching threads, and backing fibre cross-over regions is required, as well as new approaches to control the positions of UD fibres. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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16 pages, 4869 KiB

Open AccessArticle

Evolution of Electrochemical Cell Designs for In-Situ and Operando 3D Characterization

by Chun Tan, Sohrab R. Daemi, Oluwadamilola O. Taiwo, Thomas M. M. Heenan, Daniel J. L. Brett and Paul R. Shearing

Materials 2018, 11(11), 2157; https://doi.org/10.3390/ma11112157 - 1 Nov 2018

Cited by 43 | Viewed by 7820

Abstract

Lithium-based rechargeable batteries such as lithium-ion (Li-ion), lithium-sulfur (Li-S), and lithium-air (Li-air) cells typically consist of heterogenous porous electrodes. In recent years, there has been growing interest in the use of in-situ and operando micro-CT to capture their physical and chemical states in [...] Read more.

Lithium-based rechargeable batteries such as lithium-ion (Li-ion), lithium-sulfur (Li-S), and lithium-air (Li-air) cells typically consist of heterogenous porous electrodes. In recent years, there has been growing interest in the use of in-situ and operando micro-CT to capture their physical and chemical states in 3D. The development of in-situ electrochemical cells along with recent improvements in radiation sources have expanded the capabilities of micro-CT as a technique for longitudinal studies on operating mechanisms and degradation. In this paper, we present an overview of the capabilities of the current state of technology and demonstrate novel tomography cell designs we have developed to push the envelope of spatial and temporal resolution while maintaining good electrochemical performance. A bespoke PEEK in-situ cell was developed, which enabled imaging at a voxel resolution of ca. 230 nm and permitted the identification of sub-micron features within battery electrodes. To further improve the temporal resolution, future work will explore the use of iterative reconstruction algorithms, which require fewer angular projections for a comparable reconstruction. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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17 pages, 5418 KiB

Open AccessArticle

Preservation of Bone Tissue Integrity with Temperature Control for In Situ SR-MicroCT Experiments

by Marta Peña Fernández, Enrico Dall’Ara, Alexander P. Kao, Andrew J. Bodey, Aikaterina Karali, Gordon W. Blunn, Asa H. Barber and Gianluca Tozzi

Materials 2018, 11(11), 2155; https://doi.org/10.3390/ma11112155 - 1 Nov 2018

Cited by 15 | Viewed by 4401

Abstract

Digital volume correlation (DVC), combined with in situ synchrotron microcomputed tomography (SR-microCT) mechanics, allows for 3D full-field strain measurement in bone at the tissue level. However, long exposures to SR radiation are known to induce bone damage, and reliable experimental protocols able to [...] Read more.

Digital volume correlation (DVC), combined with in situ synchrotron microcomputed tomography (SR-microCT) mechanics, allows for 3D full-field strain measurement in bone at the tissue level. However, long exposures to SR radiation are known to induce bone damage, and reliable experimental protocols able to preserve tissue properties are still lacking. This study aims to propose a proof-of-concept methodology to retain bone tissue integrity, based on residual strain determination using DVC, by decreasing the environmental temperature during in situ SR-microCT testing. Compact and trabecular bone specimens underwent five consecutive full tomographic data collections either at room temperature or 0 °C. Lowering the temperature seemed to reduce microdamage in trabecular bone but had minimal effect on compact bone. A consistent temperature gradient was measured at each exposure period, and its prolonged effect over time may induce localised collagen denaturation and subsequent damage. DVC provided useful information on irradiation-induced microcrack initiation and propagation. Future work is necessary to apply these findings to in situ SR-microCT mechanical tests, and to establish protocols aiming to minimise the SR irradiation-induced damage of bone. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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14 pages, 4564 KiB

Open AccessArticle

Time-Resolved Tomographic Quantification of the Microstructural Evolution of Ice Cream

by Jingyi Mo, Enyu Guo, D. Graham McCartney, David S. Eastwood, Julian Bent, Gerard Van Dalen, Peter Schuetz, Peter Rockett and Peter D. Lee

Materials 2018, 11(10), 2031; https://doi.org/10.3390/ma11102031 - 19 Oct 2018

Cited by 21 | Viewed by 5830

Abstract

Ice cream is a complex multi-phase colloidal soft-solid and its three-dimensional microstructure plays a critical role in determining the oral sensory experience or mouthfeel. Using in-line phase contrast synchrotron X-ray tomography, we capture the rapid evolution of the ice cream microstructure during heat [...] Read more.

Ice cream is a complex multi-phase colloidal soft-solid and its three-dimensional microstructure plays a critical role in determining the oral sensory experience or mouthfeel. Using in-line phase contrast synchrotron X-ray tomography, we capture the rapid evolution of the ice cream microstructure during heat shock conditions in situ and operando, on a time scale of minutes. The further evolution of the ice cream microstructure during storage and abuse was captured using ex situ tomography on a time scale of days. The morphology of the ice crystals and unfrozen matrix during these thermal cycles was quantified as an indicator for the texture and oral sensory perception. Our results reveal that the coarsening is due to both Ostwald ripening and physical agglomeration, enhancing our understanding of the microstructural evolution of ice cream during both manufacturing and storage. The microstructural evolution of this complex material was quantified, providing new insights into the behavior of soft-solids and semi-solids, including many foodstuffs, and invaluable data to both inform and validate models of their processing. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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18 pages, 4830 KiB

Open AccessArticle

Incipient Bulk Polycrystal Plasticity Observed by Synchrotron In-Situ Topotomography

by Henry Proudhon, Nicolas Guéninchault, Samuel Forest and Wolfgang Ludwig

Materials 2018, 11(10), 2018; https://doi.org/10.3390/ma11102018 - 18 Oct 2018

Cited by 22 | Viewed by 4474

Abstract

In this paper, we present a comprehensive 4D study of the early stage of plastic deformation in a polycrystalline binary AlLi alloy. The entire microstructure is mapped with X-ray diffraction contrast tomography, and a set of bulk grains is further studied via X-ray [...] Read more.

In this paper, we present a comprehensive 4D study of the early stage of plastic deformation in a polycrystalline binary AlLi alloy. The entire microstructure is mapped with X-ray diffraction contrast tomography, and a set of bulk grains is further studied via X-ray topotomography during mechanical loading. The observed contrast is analyzed with respect to the slip system activation, and the evolution of the orientation spread is measured as a function of applied strain. The experimental observations are augmented by the mechanical response predicted by crystal plasticity finite element simulations to analyze the onset of plasticity in detail. Simulation results show a general agreement of the individual slip system activation during loading and that comparison with experiments at the length scale of the grains may be used to fine tune the constitutive model parameters. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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17 pages, 15868 KiB

Open AccessArticle

Two-Scale Tomography Based Finite Element Modeling of Plasticity and Damage in Aluminum Foams

by Yasin Amani, Sylvain Dancette, Eric Maire, Jérôme Adrien and Joël Lachambre

Materials 2018, 11(10), 1984; https://doi.org/10.3390/ma11101984 - 15 Oct 2018

Cited by 11 | Viewed by 3667

Abstract

In this study, finite element (FE) modeling of open-cell aluminum foams in tension was performed based on laboratory X-ray tomography scans of the materials at two different scales. High-resolution stitching tomography of the initial state allowed local intermetallic particles to be distinguished from [...] Read more.

In this study, finite element (FE) modeling of open-cell aluminum foams in tension was performed based on laboratory X-ray tomography scans of the materials at two different scales. High-resolution stitching tomography of the initial state allowed local intermetallic particles to be distinguished from internal defects in the solid phase of the foam. Lower-resolution scans were used to monitor the deformation and fracture in situ during loading. 3D image-based FE models of the foams were built to simulate the tensile behavior using a new microstructure-informed Gurson–Tvergaard–Needleman model. The new model allows quantitative consideration of the local presence of brittle intermetallic particles in the prediction of damage. It performs well in the discrimination of potential fracture zones in the foam, and can be easily adapted to any type of architectured material where both the global architecture and local microstructural details should be taken into account in the prediction of damage behavior. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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10 pages, 5135 KiB

Open AccessArticle

Mechanical Properties and In Situ Deformation Imaging of Microlattices Manufactured by Laser Based Powder Bed Fusion

by Anton Du Plessis, Dean-Paul Kouprianoff, Ina Yadroitsava and Igor Yadroitsev

Materials 2018, 11(9), 1663; https://doi.org/10.3390/ma11091663 - 9 Sep 2018

Cited by 33 | Viewed by 4641

Abstract

This paper reports on the production and mechanical properties of Ti6Al4V microlattice structures with strut thickness nearing the single-track width of the laser-based powder bed fusion (LPBF) system used. Besides providing new information on the mechanical properties and manufacturability of such thin-strut lattices, [...] Read more.

This paper reports on the production and mechanical properties of Ti6Al4V microlattice structures with strut thickness nearing the single-track width of the laser-based powder bed fusion (LPBF) system used. Besides providing new information on the mechanical properties and manufacturability of such thin-strut lattices, this paper also reports on the in situ deformation imaging of microlattice structures with six unit cells in every direction. LPBF lattices are of interest for medical implants due to the possibility of creating structures with an elastic modulus close to that of the bones and small pore sizes that allow effective osseointegration. In this work, four different cubes were produced using laser powder bed fusion and subsequently analyzed using microCT, compression testing, and one selected lattice was subjected to in situ microCT imaging during compression. The in situ imaging was performed at four steps during yielding. The results indicate that mechanical performance (elastic modulus and strength) correlate well with actual density and that this performance is remarkably good despite the high roughness and irregularity of the struts at this scale. In situ yielding is visually illustrated. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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14 pages, 4219 KiB

Open AccessArticle

An X-ray Tomographic Study of Rechargeable Zn/MnO₂ Batteries

by Markus Osenberg, Ingo Manke, André Hilger, Nikolay Kardjilov and John Banhart

Materials 2018, 11(9), 1486; https://doi.org/10.3390/ma11091486 - 21 Aug 2018

Cited by 10 | Viewed by 4635

Abstract

We present non-destructive and non-invasive in operando X-ray tomographic investigations of the charge and discharge behavior of rechargeable alkaline-manganese (RAM) batteries (Zn-MnO₂ batteries). Changes in the three-dimensional structure of the zinc anode and the MnO₂ cathode material after several charge/discharge cycles [...] Read more.

We present non-destructive and non-invasive in operando X-ray tomographic investigations of the charge and discharge behavior of rechargeable alkaline-manganese (RAM) batteries (Zn-MnO₂ batteries). Changes in the three-dimensional structure of the zinc anode and the MnO₂ cathode material after several charge/discharge cycles were analyzed. Battery discharge leads to a decrease in the zinc particle sizes, revealing a layer-by-layer dissolving behavior. During charging, the particles grow again to almost their initial size and shape. After several cycles, the particles sizes slowly decrease until most of the particles become smaller than the spatial resolution of the tomography. Furthermore, the number of cracks in the MnO₂ bulk continuously increases and the separator changes its shape. The results are compared to the behavior of a conventional primary cell that was also charged and discharged several times. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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15 pages, 12628 KiB

Open AccessArticle

In-Situ High Resolution Dynamic X-ray Microtomographic Imaging of Olive Oil Removal in Kitchen Sponges by Squeezing and Rinsing

by Abhishek Shastry, Paolo E. Palacio-Mancheno, Karl Braeckman, Sander Vanheule, Ivan Josipovic, Frederic Van Assche, Eric Robles, Veerle Cnudde, Luc Van Hoorebeke and Matthieu N. Boone

Materials 2018, 11(8), 1482; https://doi.org/10.3390/ma11081482 - 20 Aug 2018

Cited by 8 | Viewed by 6276

Abstract

Recent advances in high resolution X-ray tomography (μCT) technology have enabled in-situ dynamic μCT imaging (4D-μCT) of time-dependent processes inside 3D structures, non-destructively and non-invasively. This paper illustrates the application of 4D-μCT for visualizing the removal of fatty liquids from kitchen sponges made [...] Read more.

Recent advances in high resolution X-ray tomography (μCT) technology have enabled in-situ dynamic μCT imaging (4D-μCT) of time-dependent processes inside 3D structures, non-destructively and non-invasively. This paper illustrates the application of 4D-μCT for visualizing the removal of fatty liquids from kitchen sponges made of polyurethane after rinsing (absorption), squeezing (desorption) and cleaning (adding detergents). For the first time, time-dependent imaging of this type of system was established with sufficiently large contrast gradient between water (with/without detergent) and olive oil (model fat) by the application of suitable fat-sensitive X-ray contrast agents. Thus, contrasted olive oil filled sponges were rinsed and squeezed in a unique laboratory loading device with a fluid flow channel designed to fit inside a rotating gantry-based X-ray μCT system. Results suggest the use of brominated vegetable oil as a preferred contrast agent over magnetite powder for enhancing the attenuation coefficient of olive oil in a multi fluid filled kitchen sponge. The contrast agent (brominated vegetable oil) and olive oil were mixed and subsequently added on to the sponge. There was no disintegration seen in the mixture of contrast agent and olive oil during the cleaning process by detergents. The application of contrast agents also helped in accurately tracking the movement and volume changes of soils in compressed open cell structures. With the in house-built cleaning device, it was quantified that almost 99% of cleaning was possible for contrasted olive oil (brominated vegetable oil with olive oil) dispersed in the sponge. This novel approach allowed for realistic mimicking of the cleaning process and provided closer evaluation of the effectiveness of cleaning by detergents to minimize bacterial growth. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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18 pages, 2341 KiB

Open AccessFeature PaperArticle

Dynamic Tomographic Reconstruction of Deforming Volumes

by Clément Jailin and Stéphane Roux

Materials 2018, 11(8), 1395; https://doi.org/10.3390/ma11081395 - 9 Aug 2018

Cited by 22 | Viewed by 4695

Abstract

The motion of a sample while being scanned in a tomograph prevents its proper volume reconstruction. In the present study, a procedure is proposed that aims at estimating both the kinematics of the sample and its standard 3D imaging from a standard acquisition [...] Read more.

The motion of a sample while being scanned in a tomograph prevents its proper volume reconstruction. In the present study, a procedure is proposed that aims at estimating both the kinematics of the sample and its standard 3D imaging from a standard acquisition protocol (no more projection than for a rigid specimen). The proposed procedure is a staggered two-step algorithm where the volume is first reconstructed using a “Dynamic Reconstruction” technique, a variant of Algebraic Reconstruction Technique (ART) compensating for a “frozen” determination of the motion, followed by a Projection-based Digital Volume Correlation (P-DVC) algorithm that estimates the space/time displacement field, with a “frozen” microstructure and shape of the sample. Additionally, this procedure is combined with a multi-scale approach that is essential for a proper separation between motion and microstructure. A proof-of-concept of the validity and performance of this approach is proposed based on two virtual examples. The studied cases involve a small number of projections, large strains, up to 25%, and noise. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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13 pages, 4712 KiB

Open AccessArticle

Observation of Morphology Changes of Fine Eutectic Si Phase in Al-10%Si Cast Alloy during Heat Treatment by Synchrotron Radiation Nanotomography

by Shougo Furuta, Masakazu Kobayashi, Kentaro Uesugi, Akihisa Takeuchi, Tomoya Aoba and Hiromi Miura

Materials 2018, 11(8), 1308; https://doi.org/10.3390/ma11081308 - 28 Jul 2018

Cited by 13 | Viewed by 3447

Abstract

A series of three-dimensional morphology changes of fine eutectic Si-particles during heat treatment have been investigated in Self-modified and Sr-modified Al-10%Si cast alloys by means of synchrotron radiation nanotomography utilizing a Fresnel zone plate and a Zernike phase plate in this study. The [...] Read more.

A series of three-dimensional morphology changes of fine eutectic Si-particles during heat treatment have been investigated in Self-modified and Sr-modified Al-10%Si cast alloys by means of synchrotron radiation nanotomography utilizing a Fresnel zone plate and a Zernike phase plate in this study. The coral-like shape particles observed in Sr-modified cast alloy fragmented at branch and neck during heat treatment at 773 K. The fragmentation occurred up to 900 s. After that, the fragmented particles grew and spheroidized by Ostwald ripening. On the other hand, rod-like shaped eutectic Si-particles observed in self-modified cast alloy were larger in size compared with the particle size in Sr-modified cast alloy. Separation of eutectic Si-particles in Self-modified cast alloy occurred up to approximately 900 s, which was similar tendency to that in Sr-modified cast alloy. However, it was found that the morphology change behavior was very complex in rod-like shape Si-particles. The three-dimensional morphology changes of fine eutectic Si-particles in both cast alloys, specifically fragmentation and spheroidizing, can be connected to changes in mechanical properties. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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14 pages, 6700 KiB

Open AccessArticle

In-Situ X-ray Tomography Observation of Structure Evolution in 1,3,5-Triamino-2,4,6-Trinitrobenzene Based Polymer Bonded Explosive (TATB-PBX) under Thermo-Mechanical Loading

by Zeng-Nian Yuan, Hua Chen, Jing-Ming Li, Bin Dai and Wei-Bin Zhang

Materials 2018, 11(5), 732; https://doi.org/10.3390/ma11050732 - 4 May 2018

Cited by 19 | Viewed by 4460

Abstract

In order to study the fracture behavior and structure evolution of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB)-based polymer bonded explosive in thermal-mechanical loading, in-situ studies were performed on X-ray computed tomography system using quasi-static Brazilian test. The experiment temperature was set from −20 °C to 70 °C. [...] Read more.

In order to study the fracture behavior and structure evolution of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB)-based polymer bonded explosive in thermal-mechanical loading, in-situ studies were performed on X-ray computed tomography system using quasi-static Brazilian test. The experiment temperature was set from −20 °C to 70 °C. Three-dimensional morphology of cracks at different temperatures was obtained through digital image process. The various fracture modes were compared by scanning electron microscopy. Fracture degree and complexity were defined to quantitatively characterize the different types of fractures. Fractal dimension was used to characterize the roughness of the crack surface. The displacement field of particles in polymer bonded explosive (PBX) was used to analyze the interior structure evolution during the process of thermal-mechanical loading. It was found that the brittleness of PBX reduced, the fracture got more tortuous, and the crack surface got smoother as the temperature rose. At lower temperatures, especially lower than glass transition temperature of binders, there were slipping and shear among particles, and particles tended to displace and disperse; while at higher temperatures, especially above the glass transition temperature of binders, there was reorganization of particles and particles tended to merge, disperse, and reduce sizes, rather than displacing. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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Review

Jump to: Research

26 pages, 6705 KiB

Open AccessReview

Correlation of Materials Property and Performance with Internal Structures Evolvement Revealed by Laboratory X-ray Tomography

by Lei Zhang and Shaogang Wang

Materials 2018, 11(10), 1795; https://doi.org/10.3390/ma11101795 - 21 Sep 2018

Cited by 46 | Viewed by 6345

Abstract

Although X-rays generated from a laboratory-based tube cannot be compared with synchrotron radiation in brilliance and monochromaticity, they are still viable and accessible in-house for ex situ or interrupted in situ X-ray tomography. This review mainly demonstrates recent works using laboratory X-ray tomography [...] Read more.

Although X-rays generated from a laboratory-based tube cannot be compared with synchrotron radiation in brilliance and monochromaticity, they are still viable and accessible in-house for ex situ or interrupted in situ X-ray tomography. This review mainly demonstrates recent works using laboratory X-ray tomography coupled with the measurements of properties or performance testing under various conditions, such as thermal, stress, or electric fields. Evolvements of correlated internal structures for some typical materials were uncovered. The damage features in a graded metallic 3D mesh and a metallic glass under mechanical loading were revealed and investigated. Micro-voids with thermal treatment and void healing phenomenon with electropulsing were clearly demonstrated and quantitatively analyzed. The substance transfer around an electrode of a Li-S battery and the protective performance of a Fe-based metallic glass coating on stainless steel were monitored through electrochemical processes. It was shown that in situ studies of the laboratory X-ray tomography were suitable for the investigation of structure change under controlled conditions and environments. An extension of the research for in situ laboratory X-ray tomography can be expected with supplementary novel techniques for internal strain, global 3D grain orientation, and a fast tomography strategy. Full article

(This article belongs to the Special Issue In-Situ X-Ray Tomographic Study of Materials)

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