M. Coleman

Swansea University | SWAN · Materials Research Centre "MRC"

Localized tephra deposition in marine sequences is the product of many complex primary and secondary depositional processes. These can significantly influence the potential applicability of tephra deposits as isochronous marker horizons and current techniques, used in isolation, may be insufficient to fully unravel these processes. Here we demonstr...

The role of local microstructure is critical in materials performance and integrity in a cast alloy. The grain size and grain boundary distributions as well as local texture can create various microstructure/microtexture clusters that cause deformation localisation in the alloy. Inconel 713C nickel base superalloys are used as turbocharger turbine...

Basic research has been done on diffusion-welded joints with the overall aim of an adjusted interface design. The phase formation of aluminium alloy/magnesium alloy bonds has been revealed by X-ray diffraction, energy-dispersive spectroscopy and electron back-scatter diffraction. The presence of Al12Mg17 and Al3Mg2 phases in a bi-layer has been con...

In a grain-boundary-engineered (GBE) microstructure, ∑9 boundaries are the second most abundant boundary type. This article presents data showing that, in GBE copper, most ∑9s were special. ∑9 boundaries are also a geometrically necessary component of a GBE microstructure. It is suggested that there are competing requirements for ∑9s; during iterat...

Both one-step and subsequent multistep grain boundary engineering processing of copper have been investigated. Specimens were tensile tested to failure after each stage of processing, and the microhardness was measured. These properties were linked to measurements of both the grain boundary misorientation and grain boundary plane distribution in or...

Duplex stainless steels (DSS) are a family of stainless steel alloys that benefit from the presence of two relatively equally proportioned phases, ferrite and austenite. The alloys are designed to have an enhanced resistance to corrosion and superior strength properties in comparison to more common stainless steel alloys such as 316 L. Design engin...

The link between microstructure, crystallographic texture and mechanical properties is of substantial importance to the understanding of materials behaviour of aluminium alloys. The favoured approach to determine these relations has been electron backscatter diffraction (EBSD) and has received extensive prior attention. However, compared to convent...

In the second of a series of articles, the team behind the UK’s collaborative Discover Materials initiative report on students' perceptions of materials science and engineering.

Additive manufacturing (AM) processes are currently being investigated to determine their suitability for wider adoption in the aero engine industry where material consistency and structural integrity are essential. A key driver is the ability of AM to produce near net-shape components and complex geometries, reducing material wastage and tradition...

Correlative Microscopy combines data and imaging from various modalities (physical, chemical and crystallographic) at multiple length scales (centimetres to nanometres) and in various dimensions (2D-to-4D), providing a linked and holistic examination of samples. Here, we have utilised the correlative microscopy workflow (OM, SEM, EBSD, XRM, FIB-SEM...

Correlative imaging combines information from multiple modalities (physical-chemical-mechanical properties) at various length scales (centimetre to nanometre) to understand the complex biological materials across dimensions (2D-3D). Here, we have used numerous coupled systems: X-ray microscopy (XRM), scanning electron microscopy (SEM), electron bac...

Correlating Microstructure to in situ Micromechanical Behaviour and Toughening Strategies in Biological Materials - Volume 25 Supplement - Richard E Johnston, Ria L Mitchell, Cameron Pleydell-Pearce, Mark Coleman, Laura North, David LaBonte, Michelle Oyen, Rachel Board, Edward C Pope, Hari Arora, David Howells

The naturally-forming calcareous exoskeletons of arthropods and molluscs afford a substantial degree of protection, stability and waterproofing, while developing in ambient conditions and exhibiting diverse microstructure-property relationships. Correlative imaging combines information from multiple modalities (physical-chemical-mechanical properti...

Correlative Imaging and Bio-inspiration: Multi-scale and Multi-modal Investigations of the Acorn Barnacle (Semibalanus balanoides) - Volume 24 Supplement - Ria L. Mitchell, Cameron Pleydell-Pearce, Mark P. Coleman, Peter Davies, Laura North, Richard E. Johnston, Will Harris

Nickel-based superalloy C263 has been consolidated with Laser Powder Bed Fusion (LPBF) with two perpendicular build orientations and exposed to either of two heat treatment programmes. This study analyses the effects of build orientation and heat treatment on the resulting microstructures produced in LPBF C263 variants, evaluated against a cast equ...

With the drive towards cost-effective routes for the manufacture of engineering components, flow forming technologies are now under consideration for the production of structural axisymmetric geometries such as tubes and cones. This near net shape process is known to offer improvements in material utilisation when compared with traditional processe...

“Cuttlebone,” the internalized shell found in all members of the cephalopod family Sepiidae, is a sophisticated buoyancy device combining high porosity with considerable strength. Using a complementary suite of characterization tools, we identified significant structural, chemical, and mechanical variations across the different structural units of...

‘Cuttlebone’, the internalized shell found in all members of the cephalopod family Sepiidae, is a sophisticated buoyancy device combining high porosity with considerable strength. Using a complementary suite of characterization tools, we identified significant structural, chemical and mechanical variations across the different structural units of t...

Fatigue crack growth-based design is a significant modern engineering consideration for the transportation sector, and its implementation requires accurate characterization and understanding of crack propagation mechanisms with respect to microstructure. To support this goal, long and small fatigue crack growth studies were conducted on widely used...

Ductility regression is the main concern in using Ti-834 titanium alloy at temperatures above 500 °C for aerospace applications. The reduction of ductility in titanium alloys at high temperatures is strongly correlated to the exposure time. In the current study the effect of prolonged exposure at 500 °C on the tensile ductility of two differently p...

The effect prolonged exposure at 500?C had on the tensile ductility of the cast variation of the Ti-834 alloy was investigated. Analysis found ?2 and silicide precipitation was present in the alloy before any exposure. Exposure resulted in the alloy exhibiting a relatively uniform layer of alpha case between 5-7?m in depth after 500 hour exposure a...

The effect of thermo-mechanical history on hot compression behaviour and resulting microstructures of a nickel base superalloy is presented. Hot compression tests were carried out on HAYNES® 282® specimens to varying strains from 0.1 to 0.8. Both single pass and multi-pass tests were completed. 60 minute inter-pass times were utilized to accurately...

Grain boundary engineering (GBE) to promote degradation-resistant interfaces in the microstructure usually requires that the grain size remains small so that strength is not compromised. Aspects of grain size measurement and control will be reviewed and discussed for a variety of GBE materials such as copper, nickel, nickel-based alloys and austeni...

Many physical properties of rocks are sensitive to grain size and hence to the structure of grain boundaries. Depending on their properties, such as deformation and transport behaviour, boundaries may be divided into two broad types, namely special and general grain boundaries. Electron backscattered diffraction (EBSD) is used to investigate the mi...

Grain boundary engineering (GBE) processing schedules, involving low-strain (5% deformation) iterative treatments, have been carried out on copper. Misorientation and grain boundary plane statistics have been derived, plus tensile and hardness measurements. The Σ3 length fraction and Σ9/Σ3 number ratio decreased during the first two processing iter...

The present route to grain boundary engineering (GBE) is usually based on multiple annealing twinning which can only be applied to a certain subset of materials, namely those that twin prolifically. A more general approach has been highlighted recently, following experimental evidence that certain boundary planes in iron bicrystals are ‘special’, a...

The five-parameter grain boundary distributions of grain boundary engineered nickel and copper specimens have been analyzed in detail. The relative areas of {111} planes in the entire population did not increase as a result of grain boundary engineering (GBE) and, in the Σ3-excluded population, decreased after GBE. This decrease occurred because th...

Iterative processing, involving sequential deformation and annealing, has been carried out on copper specimens with the aim of grain boundary engineering (GBE) them. The data have provided some interesting insights into the mechanisms of GBE. The results have demonstrated that development of a high proportion of Σ3s is beneficial to properties, as...