arXiv subjects

Ben Britton

Publications and source records attributed to Ben Britton.

11 recordsLinked to original sources

arXiv2026

Correlative Microstructural Analysis of a Weathered Nantan Meteorite Fragment

The weathering of iron-rich phases within meteorites is a process that significantly alters the microstructure and chemical composition based on the environmental conditions at the location of landing and exposure time since fall. This work investigates the resulting phases in a correlative and comparative manner using a Nantan meteorite fragment. Techniques including X-ray Photoelectron Spectroscopy, Energy Dispersive X-ray Spectroscopy, and X-ray Fluorescence Spectroscopy were used for compositional determination and X-ray Diffraction and Electron Backscatter Diffraction for phase determination and microstructural analysis. These techniques revealed the meteorite matrix to be predominantly composed of magnetite, with distinct regions of high Ni content. The grain size was found to be approximately 5 $\mu$m in $\geq$ 2.6 at$\%$ Ni content regions with a visible boundary of 100-200 $\mu$m extending into $\leq$ 0.9 at$\%$ Ni regions, wherein the grain size averaged 10s of $\mu$m. Additionally, a brecciated cohenite phase was found with a vein-line structure, composed of NiO, magnetite, and deposits of iron and nickel carbonates. This indicates that the matrix regions formed through the weathering of discrete primary phases, with the high Ni regions forming from aqueous alteration of kamacite and the low Ni regions forming from direct dissolution and oxidation of the source Fe-Ni metal.

physics.geo-ph↗

arXiv2026

The role of austenite twins on variant selection during bainitic decomposition of a low carbon (0.06 wt%) steel

Thermomechanical Controlled Processing (TMCP) is widely used to control the microstructure and properties of linepipe or high strength low alloy steels (HSLA). These steels are often joined by welding and used in demanding environments such as the Arctic. In these materials, the thermal path the steel experiences is critical for understanding microstructural evolution during processing. A key step is the solid-state phase transformation during cooling from the high-temperature austenite to the room-temperature microstructure which significantly influences the final mechanical properties. We used 3D electron backscatter diffraction (EBSD) to explore the relationship between the austenite phase and the room temperature microstructure. A significant result for the present work is the collection, and analysis, of data from a large volume (150 x 150 x 100 um3, with a (200 nm)3 voxel size) which enables analysis of a complete prior austenite grain. This grain is twinned, allowing us to analyse the variants at the twin boundary in this grain, which offers new insights into the mechanisms of the transformation to the low temperature phase by highlighting the significant of the twin boundaries on the variants present. This suggests opportunities to engineer novel microstructures by controlling the high-temperature grain boundary character.

cond-mat.mtrl-sci↗

arXiv2025

Angular Resolution Enhancement of Electron Backscatter Diffraction Patterns

We present a simple 'shift-and-add' based improvement in the angular resolution of single electron backscatter diffraction (EBSD) patterns. Sub-pixel image registration is used to measure the (sub-pixel) difference in projection parameters for patterns collected within a map, and then the pattern is shifted and added together. The resultant EBSD-pattern is shown to contain more angular information than a long-exposure single pattern, via 2D Fast Fourier Transform (FFT)-based analysis. In particular, this method has the potential to enhance the scope of small compact direct electron detectors (DEDs).

physics.ins-det↗

arXiv2025

Large volume 'chunk' lift out for 3D tomographic analysis using analytical plasma focussed ion beam -- scanning electron microscopy

Characterization of the structure and properties of materials in three dimensions, including grains and the residual pattern of deformation, provides necessary information required to guide materials design as well as support materials modelling efforts. In this work, we present an overview of site-specific large volume 'chunk' lift out and 3D serial sectioning of substantive volumes (e.g. 200 x 200 x 400 um3), where sectioning is optimized for 3D electron backscatter diffraction (EBSD) based crystallographic analysis, using a plasma (Xe) focussed ion beam scanning electron microscope (plasma FIB-SEM) equipped to perform EBSD using a 'static' configuration (i.e. slicing and EBSD-mapping are performed without moving the sample). This workflow is demonstrated through the 3D plasma FIB-SEM based EBSD analysis of an indent made within a polycrystal of pure magnesium. The lift out approach is suitable for a wide range of materials, and we offer a step-by-step guide within the present work to provide opportunity for others to more easily enter this field and collect valuable data.

cond-mat.mtrl-sci↗

arXiv2025

Practical considerations for crystallographic and microstructure mapping with direct electron detector-based electron backscatter diffraction

Compact direct electron detectors are becoming increasingly popular in electron microscopy applications including electron backscatter diffraction, as they offer an opportunity for low cost and accessible microstructural analysis. In this work, we explore how one of these commercial devices based on the Timepix chip can be optimized to obtain high quality data quickly and easily, through careful systematic analysis of a variety of samples, including: semiconductor silicon, commercially pure nickel, a dual phase titanium-molybdenum alloy, and a silicon carbide ceramic matrix composite. Our findings provide strategies for very fast collection of orientation maps, including at low voltage (5-10 keV) and low beam current conditions. Additionally, strategies for collection of very high quality EBSD patterns are demonstrated that have significant potential for advanced EBSD applications (e.g. elastic strain mapping).

cond-mat.mtrl-sci↗

arXiv2023

Characterisation of the strain rate sensitivity of basal, prismatic and pyramidal slip in Zircaloy-4 using micropillar compression

The slip strength of individual slip systems at different strain rates will control the mechanical response and strongly influence the anisotropy of plastic deformation. In this work, the slip activity and strain rate sensitivity of the basal, prismatic, and pyramidal slip systems are explored by testing at variable strain rates (from 10E-4 s^-1 to 125 s^-1) using single crystal micropillar compression tests. These systematic experiments enable the direct fitting of the strain rate sensitivities of the different slips using a simple analytical model and this model reveals that deformation in polycrystals will be accommodated using different slip systems depending on the strain rate of deformation in addition to the stress state (i.e. Schmid's law). It was found that the engineering yield stress increases with strain rate, and this varied by slip systems. Activation of the prismatic slip system results in a high density of parallel, clearly discrete slip planes, while the activation of the pyramidal slip leads to the plastic collapse of the pillar, leading to a 'mushroom' morphology of the deformed pillar. This characterization and model provide insight that helps inform metal forming and understanding of the mechanical performance of these engineering alloys in the extremes of service conditions.

cond-mat.mtrl-sci↗

arXiv2021

Development of local plasticity around voids during tensile deformation

Voids can limit the life of engineering components. This motivates us to understand local plasticity around voids in a nickel base superalloy combining experiments and simulations. Single crystal samples were deformed in tension with in-situ high angular resolution electron back scatter diffraction to probe the heterogeneous local stress field under load; the reference stress is informed by crystal plasticity finite element simulations. This information is used to understand the activation of plastic deformation around the void. Our investigation indicates that while the resolved shear stress would indicate slip activity on multiple slip systems, slip is reduced to specific systems due to image forces and forest hardening. This study rationalizes the observed development of plastic deformation around the void, aiding in our understanding of component failure and engineering design.

cond-mat.mtrl-sci↗

arXiv2021

Casting voids in nickel superalloy and the mechanical behaviour under room temperature tensile deformation

The microstructure of a second-generation nickel base superalloy is studied using X-ray computed tomography (XCT) and scanning electron microscopy (SEM). The as-cast material contains 0.15 (+-0.001) vol% voids and these are distributed in the inter-dendritic region. The volume fraction of the voids increases to 0.21 (+-0.001) vol% after tensile deformation. Surface observations show evidence of dislocation emissions from the void surface, a mechanism possibly facilitates the expansion of the voids and contributes to the increased void volume fraction. Phenomenological parameters such as stress triaxiality, often believed to control void growth, are investigated through crystal plasticity simulation and compared with literature reported data. The results indicate weak correlation between stress triaxiality and void growth, but this may be possibly due to the lack of data at higher level of plastic deformation, which is limited by the ductility of the material. The distribution of the stress triaxiality field within the sample is heterogeneous and the peak of the triaxiality field is a function of the ratio between notch diameter and sample width. A smaller notch diameter to sample width ratio tend to distribute the triaxiality peaks towards the centre of the sample but also lead to higher strain localisation, an effect that results in early sample failure.

cond-mat.mtrl-sci↗

arXiv2019

Understanding plasticity in zirconium using in-situ measurement of lattice rotations

Understanding deformation in polycrystalline metals is critical to use them in high-value high-risk applications. We present in-situ characterisation of plastic deformation of zirconium, a hexagonal closed packed (HCP), metal. Analysis of plastic deformation is performed using electron backscatter diffraction (EBSD) to reveal changes in lattice orientation. Through implementation of TrueEBSD, we can relate the lattice rotations back to the undeformed reference frame. This enables us to explore which slip systems are active and the degree of homogeneous (i.e. deformation with respect to the external load) and heterogeneous (i.e. deformation with respect to the local grain neighbourhood). Additionally, from our analysis, we notice that lattice rotations consistent with a significant fraction pyramidal slip are found. These results are placed in the context of deformation and performance of HCP alloys and zirconium alloys used as nuclear fuel cladding.

cond-mat.mtrl-sci↗

arXiv2018

Space rocks and optimising scanning electron channelling contrast

Forescatter electron imaging is a popular microscopy technique, especially for scanning electron microscopes equipped with an electron backscatter diffraction detector. In principal, this method enables qualitative imaging of microstructure but quantitative assessment can be limited due to limited information about the contrast afforded. In this work, we explore forescatter electron imaging and demonstrate that imaging can be optimised for topographic, phase, and subtle orientation contrast imaging through appropriate sample and detector positioning. We demonstrate the relationship between imaging modes using systematic variation in detector positioning and compare this with pseudo-forescatter electron images, obtained from image analysis of diffraction patterns, to explore and confirm image contrast modes. We demonstrate these contrast mechanisms on a map obtained from a sample of the Gibeon meteorite.

cond-mat.mtrl-sci↗

arXiv2018

Characterisation of slip and twinning in high rate deformed zirconium with electron backscatter diffraction

Zirconium alloys are used in the nuclear industry as structural materials, and can be subject to high strain rate loading conditions during forming and in the case of a reactor accident. In this context, the relationship between strain rate dependent mechanical properties, crystallographic texture and deformation modes, such as slip and deformation twinning, are explored in this work. Commercially pure zirconium is deformed to 10 % engineering strain under quasi-static and high strain rate loading, and post-mortem analysis of the samples is performed using electron backscatter diffraction (EBSD) to observe different twin and slip systems activated. Twin types are identified from local intergranular misorientation maps, and active slip systems are identified from long range intragranular misorientation maps. We link characterisation of the mechanical responses, twin types and morphologies, and relative slip system activation as a function of loading mode. We find that variations in strength and hardening can be related to the relative propensity of twinning and the number of active slip systems.

cond-mat.mtrl-sci↗