In-situ investigations of structural changes during cyclic loading by high resolution reciprocal space mapping

A major failure reason for structural materials is fatigue-related damage due to repeatedly changing mechanical loads. During cyclic loading dislocations self-organize into characteristic ordered structures, which play a decisive role for the materials lifetime. These heterogeneous dislocation structures can be identified using advanced electron microscopy and synchrotron techniques. A detailed characterization of the microstructure during cyclic loading by in-situ monitoring the internal structure within individual grains with high energy x-rays can help to understand and predict the materials behavior during cyclic deformation and to improve the material design. While monitoring macroscopic stress and strain during cyclic loading, reciprocal space maps of diffraction peaks from single grains are obtained with high resolution. High Resolution Reciprocal Space Mapping was applied successfully in-situ during cyclic deformation of macroscopic aluminium samples at the Advanced Photon Source to reveal the structural reorganization within single grains embedded in the bulk material during fatigue

Monitoring microstructural evolution in-situ during cyclic deformation by high resolution reciprocal space mapping

The recently developed synchrotron technique High Resolution Reciprocal Space Mapping (HRRSM) is used to characterize the deformation structures evolving during cyclic deformation of commercially pure, polycrystalline aluminium AA1050. Insight into the structural reorganization within single grains is gained by in-situ monitoring of the microstructural evolution during cyclic deformation. By HRRSM, a large number of individual subgrains can be resolved within individual grains in the bulk of polycrystalline specimens and their fate, their individual orientation and elastic stresses, tracked during different loading regimes as tension and compression. With this technique, the evolution of dislocation structures in selected grains was followed during an individual load cycle

High-Resolution Single-Grain Diffraction of Polycrystalline Materials

Polycrystalline bulk materials are ubiquitous in everyday life, including biological, geological, and engineered structural and functional materials. Their fundamental units are individual grains, which are characterized by their microstructure; i.e., the arrangement of lattice defects. The microstructure usually influences the materials properties critically

Strategic sustainable development in the UK construction industry, through the Framework of Strategic Sustainable Development, using Building Information Modelling

The UK Government has set out ambitious plans for all new domestic and commercial buildings to be zero carbon rated by 2016 and 2020 respectively. These are some of the most progressive environmental targets for the built environment in the western world. There are also sustainability principles (SP) that need to be addressed by the UK construction industry, particularly negative impacts such as waste and pollution. Currently, 100 million tonnes of construction waste, including 13 million tonnes of unused materials, is generated each year, with only 20% currently capable of being recycled. The majority of this waste ends up in landfill, contributing to further pollution of the biosphere. The literature suggests that these negative impacts result from a variety of causes, including ineffective leadership, ingrained cultures, outdated technologies and poor logistics. There are a number of innovative projects within the UK, particularly at a local level, that pose the question as to whether bottom up approaches may be more successful than top down policies, as set by national and local government. This paper presents a case study demonstrating the former approach within the construction industry. Research and consultancy has been undertaken collaboratively between industry, academia and professional practice in the production of 15 individually designed sustainable dwellings in the North East of England. This project has employed Building Information Modelling (BIM) as a new collaborative working platform, aligned to the Modern Method of Construction (MMC). By situating this inquiry within an authentic case study it has highlighted currently ineffective strategies, policies and leadership which have prevented full exploitation of the potential of BIM and MMC towards sustainable production. This inquiry supports the integration of the Framework of Sustainable Strategic Development (FSSD) into construction procurement, as a method for implementing bottom up leadership in a value driven project

Anisotropic strain variations during the confined growth of Au nanowires

The electrochemical growth of Au nanowires in a template of nano-porous anodic aluminum oxide was investigated in situ by means of grazing-incidence transmission small- and wide-angle x-ray scattering (GTSAXS and GTWAXS), x-ray fluorescence (XRF) and 2-dimensional surface optical reflectance (2D-SOR). The XRF and the overall intensity of the GTWAXS patterns as a function of time were used to monitor the progress of the electrodeposition. Furthermore, we extracted powder diffraction patterns in the direction of growth and in the direction of confinement to follow the evolution of the direction-dependent strain. Quite rapidly after the beginning of the electrodeposition, the strain became tensile in the vertical direction and compressive in the horizontal direction, which showed that the lattice deformation of the nanostructures can be artificially varied by an appropriate choice of the deposition time. By alternating sequences of electrodeposition to sequences of rest, we observed fluctuations of the lattice parameter in the direction of growth, attributed to stress caused by electromigration.. Furthermore, the porous domain size calculated from the GTSAXS patterns was used to monitor how homogeneously the pores were filled.Comment: Short communication manuscript. Four figure

Powder diffraction computed tomography: A combined synchrotron and neutron study

Diffraction and imaging using x-rays and neutrons are widely utilized in different fields of engineering, biology, chemistry and/or materials science. The additional information gained from the diffraction signal by x-ray diffraction and computed tomography (XRD-CT) can give this method a distinct advantage in materials science applications compared to classical tomography. Its active development over the last decade revealed structural details in a non-destructive way with unprecedented sensitivity. In the current contribution an attempt to adopt the well-established XRD-CT technique for neutron diffraction computed tomography (ND-CT) is reported. A specially designed \u27phantom\u27, an object displaying adaptable contrast sufficient for both XRD-CT and ND-CT, was used for method validation. The feasibility of ND-CT is demonstrated, and it is also shown that the ND-CT technique is capable to provide a non-destructive view into the interior of the \u27phantom\u27 delivering structural information consistent with a reference XRD-CT experiment

Characterization of Irradiation Damage Using X-Ray Diffraction Line-Profile Analysis

During operation, structural components made of zirconium alloys are subject toneutron irradiation, which leads to the displacement of zirconium atoms fromtheir lattice sites, the production of self-interstitials and vacancies, and eventually dislocation loops. This process can lead to deleterious effects such as irradiation growth, creep, and embrittlement as well as accelerated aqueous corrosion. Quantitative analysis of dislocation line densities is seen as an importantpathway for distinguishing between the irradiation response of different alloys.The analysis of irradiation damage using X-ray diffraction (XRD) line-profile analysis has proven to be a powerful complementary technique to transmissionelectron microscopy, which samples a comparatively large volume and is lessaffected by the subjectivity of image analysis. In this paper we present andanalyze three different types of XRD experiments, describing their purpose andthe new insight achieved using each technique. First, we present work carriedout on neutron-irradiated samples, comparing dislocation line densities measured by XRD with macroscopic growth measurements. A second experimentusing a synchrotron-based X-ray microbeam enabled the mapping of dislocationline densities as a function of depth from the surface of proton-irradiated zirconium alloys. These data are compared with calculated damage profiles, providingnew insight into the early saturation of damage. Finally, the last example presented here focuses on synchrotron-based 3D XRD measurements, for whichdislocation-loop line densities were analyzed in hundreds of individual grains,providing excellent statistics about the grain-to-grain variability of line densities

In situ\textit{In situ} hydride breathing during the template-assisted electrodeposition of Pd nanowires

We investigated the structural evolution of electrochemically fabricated Pd nanowires $\textit{in situ}$ by means of grazing-incidence transmission small- and wide-angle x-ray scattering (GTSAXS and GTWAXS), x-ray fluorescence (XRF) and 2-dimensional surface optical reflectance (2D-SOR). This shows how electrodeposition and the hydrogen evolution reaction (HER) compete and interact during Pd electrodepositon. During the bottom-up growth of the nanowires, we show that $\beta$-phase Pd hydride is formed. Suspending the electrodeposition then leads to a phase transition from $\beta$- to $\alpha$-phase Pd hydride. Additionally, we find that grain coalescence later hinders the incorporation of hydrogen in the Pd unit cell. GTSAXS and 2D-SOR provide complementary information on the volume fraction of the pores occupied by Pd, while XRF was used to monitor the amount of Pd electrodeposited.Comment: 17 pages, 11 figures, 4 appendice

Lithium distribution and transfer in high-power 18650-type Li-ion cells at multiple length scales

The distribution of lithium inside electrodes of a commercial Li-ion battery of 18650-type with LiFePO$_{4}$ cathode and graphite anode is investigated on different length scales using neutron diffraction, X-ray (synchrotron-based) diffraction and X-ray computed tomography. Evolution of 2D (in-plane) lithium distribution in lithiated graphite is monitored during charge/discharge using millimeter-sized spatial resolution. Micrometer-sized details of cell organization and lithiation of both the positive and negative electrodes are obtained from diffraction-based tomography applying synchrotron radiation. In-situ lithiation of the cathode over its thickness and development of the lithium concentration front during cell charge/discharge is traced by diffraction-based profiling with a micrometer-sized synchrotron beam in a single-layer electrochemical cell