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A role with MAPP means being part of a large, growing and well-networked multidisciplinary team working with leading universities, industry partners and High Value Manufacturing Catapult (HVMC) centres.

MAPP’s cohort of researchers works together to solve some of the fundamental challenges limiting the uptake of a vital class of new and emerging technologies in ceramics, metals and polymers.

The hub’s collaborative approach draws in expertise from materials science, automatic control and systems engineering, mechanical engineering, the Henry Royce Institute, the UK's national synchrotron - the Diamond Light Source and our close working relationships with industry partners including GKN, Renishaw and Rolls-Royce.

MAPP is recoupling manufacturing process development with the underpinning materials science, with a research programme spanning the fundamentals of powder materials, advanced in-situ process monitoring and characterisation, and new approaches to modelling and control.

CURRENT OPPORTUNITIES

PhD Position - Coupled homogenization and precipitation kinetics during additive manufacture and processing

The additive manufacture of metal alloys through powder processing is an exciting field where the potential benefits to industry are numerous and the scientific problems are challenging. The process is complicated by the rapid rate of melting and solidification and the stochastic interaction between the heat source and powder. The resulting microstructure is heterogeneous with strong anisotropy. The additive manufacture of precipitate strengthened alloys such as Nickel-based superalloys are particularly challenging as the chemical segregation that develops in AM conditions result in undesirable anomalous precipitation kinetics. Careful post heat treatment is required to obtain a homogeneous precipitate dispersion. The size and spatial arrangement of the precipitates impact mechanical properties and is important when considering yield, creep, and fatigue properties.

This work aims to develop accurate descriptions of precipitation that is coupled with the formation and homogenization of the chemical segregation. The main application of the developed model will be the design and optimization of post-processing steps for a given additive manufactured nickel-based superalloy. To meet this objective, a computation materials engineering framework will be developed that couples fluid dynamics descriptions of liquation and solidification stages of the process to finite element modelling of heat transfer to determine the boundary conditions for the formation of chemical segregation and precipitation. Interface tracking as well as statistical models of precipitate evolution will be used to study their kinetics.

This PhD project is funded by the University of Sheffield and aligned to the MAPP EPSRC Future Manufacturing Hub, as a project within the cross-cutting theme of Modelling, Optimization and Control. MAPP provides access to advanced 3D printing facilities with state of the art process control and monitoring. The work also has the opportunity to utilize advanced characterization methods available within the Royce Centre, where the University of Sheffield is the lead partner in the Advanced Metals Processing research theme.

Click here to apply online. Application deadline 30th April 2020.

 

PhD Position - Development of methodologies to accelerate alloy design for additive manufacturing

The ability to produce parts with complex geometries, previously inaccessible via traditional fabrication methods, has made additive manufacturing (AM) an enabling production process for a host of industries. However, the introduction of metal AM into service has been slow to develop due to the necessity for the design of alloys tailored to these manufacturing methods. The alloy development process has in turn been limited by the difficulties encountered in reliably producing metal powders and the subsequent time-consuming evaluation of AM builds before specialised testing can commence. To this end, this programme aims to create processes through which alloy design for AM can be facilitated by establishing methodologies for accelerated powder production and rapid AM build evaluation flows. Firstly, methodologies for accelerated alloy powder production will be established. Currently, alloy development programs rely on alloy compositions going through the full atomisation process, i.e. an ingot of the desired composition is produced using induction melting and subsequently atomised to achieve a powder distribution with the required characteristics. This process is time consuming and as a result only a limited number of alloys can be comprehensively evaluated in powder form. Through this project a novel methodology of producing powders will be developed whereby a solid solution master alloy will be designed, and elemental powders will be used to microalloy the powder ex situ so that a number of different alloys with varying chemistries may be obtained. This will therefore only necessitate a single atomisation step as the ex situ microalloying can be achieved using powder blending processes that are achievable in significantly faster time frames.

Following the successful production of an array of metallic powders, additive manufacturing will be used to create a set of samples to evaluate the composition’s amenability to AM processing. Whilst AM parts can be built in a number of hours, the evaluation of their characteristics is a slow and time-consuming process, and hence, evaluation flows that allow an initial assessment of AM quality are required. This project will focus on creating methods for rapid baseplate release of AM parts in order to allow characterisation using non-destructive methods for defect characterisation (X-ray computed tomography and/or acoustic or resonant ultrasound methods) as well as spectroscopy methods for chemical analysis of the alloy composition and diffraction based techniques to evaluate the initial microstructural condition of the material. This will allow the ranking and downselection of suitable compositions for further, tailored testing. In addition, the consistent characterisation of sample build using AM on platforms that allow in situ monitoring will enable a cross-correlation of monitored parameters with AM build quality to be established that can be further used to improve machine learning algorithms developed through MAPP for improved AM parameter selection.

The project will seek to demonstrate the efficacy of the methodologies described by undertaking an alloy design case study for hydrogen storage applications. Sahlberg et al. [10.1038/srep36770], highlighted the potential of the body-centred cubic high entropy alloy (HEA) system TiVZrNbHf to be used for hydrogen storage applications. Through this project, a solid solution master alloy from the TiVZrNbHf or similar systems will be designed initially by using thermodynamic models to guide the selection. This master alloy will be powder processed and subsequently a range of compositions will be created using microalloying to investigate these types of systems to develop HEA hydrides but also to explore the possibility of designing HEA Laves phases or AB5 based intermetallics that may allow improvements to be realised for hydrogen storage solutions. The compositions developed will be built on available powder bed platforms and rapidly evaluated using the combination of techniques outlined above. Promising samples will then be identified for further testing of hydrogen storage materials.

Whilst the project aims to primarily explore methods of accelerated alloy design, it may also identify promising alloys for hydrogen storage applications as well as identify methods that may provide valuable for resource efficiency in the production of metal powders requiring fewer atomisation steps.

Click here to apply online. Application deadline 30th April 2020.

 

PhD Position - Capturing additive manufacturing's laser-matter interactions

A PhD studentship is now available working on the synchrotron and neutron imaging of additive manufacturing, based at ESRF. The PhD will be a UCL one with Prof. Lee as primary supervisor. You will do several placements at Rolls-Royce UK. You will join ID19’s team at the ESRF. ID19 is a hard X-ray beamline with a special emphasis on (in situ) microtomography and ultra-high speed radiography. Working with UCL, ILL and Rolls-Royce plc, your PhD project will be to help develop, build and use in situ additive manufacturing (AM) rigs which can be used on the ESRF/ILL beamlines to perform in situ and operando imaging that will help develop new processes, materials and monitoring systems. Working with the beamline scientists at ESRF you will learn state of the art X-ray physics; with UCL you will learn how to design and apply AM rigs that work on synchrotron and neutron (with ILL) beamlines. At Rolls-Royce you will use the new physics you reveal to improve and validate computation models of the process.

The rig you will help develop will be a new generation synchrotron enabled powder bed AM machine that has enhanced capability (i.e. multi-laser, expanded correlative imaging). Using this new AM rig you will probe the AM process at the micron scale with micro-second resolution for Ti and Ni alloys, quantifying key phenomena including powder flow and melting, solidification, and microstructural feature formation. Consequently, neutron diffraction will be used to capture the development of residual stresses and solid-state phase transformations in situ during the build of complete components during experiments at ILL. The acquired data is to be used for the advancement of the two computation components: 1. multi-scale modelling of the process (developed at Rolls-Royce, but informed, validated and applied by student); and 2. the development of Machine Learning algorithms to enable ‘synchrotron calibrated’ correlative imaging process control.

Further information may be obtained from Alexander Rack (tel.: +33 (0)4 76 88 17 81, email: alexander.rack@esrf.fr) and from Prof. Peter D. Lee (tel.: +44 20 7679 3570, email: peter.lee@ucl.ac.uk).