Metallic materials are indispensable to modern human life. From everyday items such as aluminium drinks cans, to advanced applications like jet engine turbine blades and the pressure vessels of nuclear reactors, the positive social impact of metals is difficult to overstate. Yet despite major advances in our understanding of the manufacture and properties of metals, significant challenges remain. Constructing the next generation of electric cars will require improved lightweight alloys and joining technologies. Development of fusion power plants, which will provide near-limitless carbon-free energy, will require the development of advanced alloy systems capable surviving the extreme environments found inside reactors. For the next generation of hypersonic air and space vehicles, we require propulsion systems capable of over Mach 5. Alloys will need to survive 1800 degrees Celsius, be made into complex shapes, and be joined without losing any of their properties. Overcoming these challenges by improving existing metallic materials, developing new ones, and adapting manufacturing methods, then the benefits will be substantial. Now is a particularly exciting time to be involved in metallurgical research and manufacturing. This is not only because of the kinds of compelling challenges specified above, but also because of the opportunities afforded by the emergence of new advanced manufacturing technologies. Innovative techniques such as 3D printing are enabling novel shapes and design concepts to be realised, whilst the latest solid-state processes allow for the design and production of bespoke alloys that cannot be made by conventional liquid casting techniques. Industry 4.0, or the fourth industrial revolution, provides opportunities to optimise emerging and established technologies through the use of material and process data and advanced computational techniques. In order to fully exploit these opportunities, we need to understand the complex relationships between the processing, structure, properties and performance of materials, and link these to the digital manufacturing environment. To deliver the factories of tomorrow, which will be critical to the future strength of UK plc and the wider economy, industry will require more specialists with a thorough understanding of metallic materials science and engineering. These metallurgists should also have the professional and technical leadership skills to exploit emerging computational and data-driven approaches, and be well versed in equality and diversity best practice, such that they can effect positive changes in workplace culture. The EPSRC Centre for Doctoral Training in Advanced Metallic Systems will help to deliver these specialists, currently in short supply, by recruiting and training cohorts of high level scientists and engineers. Through collaboration with industry, and a comprehensive training in fundamental materials science and computational methods, professional skills, and equality and diversity best practice, our graduates will be equipped to become future research leaders and captains of industry.

In highly engineered materials, microscale defects can determine failure modes at the compo-nent/system scale. While X-ray CT is unique in being able to image, find, and follow defects non-destructively at the microscale, currently it can only do so for mm sized samples. This currently presents a significant limitation for manufacturing design and safe life prediction where the nature and location of the defects are a direct consequence of the manufacturing process. For example, in additive manufacturing, the defects made when manufacturing a test-piece may be quite different from those in a three dimensionally complex additively manufactured engineering component. Similarly, for composite materials, small-scale samples are commonly not large enough to properly represent all the hierarchical scales that control structural behaviour. This collaboration between the European Research Radiation Facility (ESRF) and the National Research Facility for laboratory CT (NRF) will lead to a million-fold increase in the volume of material that can be X-ray imaged at micrometre resolution through the development and exploitation of a new beamline (BM18). Further, this unparalleled resolution for X-rays at energies up to 400keV enables high Z materials to be probed as well as complex environmental stages. This represents a paradigm shift allowing us to move from defects in sub-scale test-pieces, to those in manufactured components and devices. This will be complemented by a better understanding of how such defects are introduced during manufacture and assembly. It will also allow us to scout and zoom manufactured structures to identify the broader defect distribution and then to follow the evolution of specific defects in a time-lapse manner as a function of mechanical or environmental loads, to learn how they lead to rapid failure in service. This will help to steer the design of smarter manufacturing processes tailored to the individual part geometry/architecture and help to establish a digital twin of additive and composite manufacturing processes. Secondly, we will exploit high frame rate imaging on ID19 exploiting the increased flux available due to the new ESRF-extremely bright source upgrade to study the mechanisms by which defects are introduced during additive manufacture and how defects can lead to very rapid failures, such as thermal runaway in batteries In this project, we will specifically focus on additive manufacturing, composite materials manufacturing and battery manufacturing and the in situ and operando performance and degradation of such manufactured articles, with the capabilities being disseminated and made more widely available to UK academics and industry through the NRF. The collaboration will also lead to the development of new data handling and analysis processes able to handle the very significant uplift in data that will be obtained and will lead to multiple site collaboration on experiments in real-time. This will enable us to work together as a multisite team on projects thereby involving less travelling and off-setting some of the constraints on demanding experiments posed by COVID-19.

Understanding and characterising the behaviour of fluids is fundamental to numerous industrial and environmental challenges with wide-ranging societal impact. The CDT in Fluid Dynamics at Leeds will provide the next generation of highly trained graduates with the technical and professional skills and knowledge needed to tackle such problems. Fluid processes are critical to both economic productivity and the health and environmental systems that affect our daily lives. For example, at the microscale, the flow of liquid through the nozzle of an ink-jet printer controls the quality of the printed product, whilst the flow of a coolant around a microprocessor determines whether or not the components will overheat. At the large scale, the atmospheric conditions of the Earth depend upon the flow of gases in the atmosphere and their interaction with the land and oceans. Understanding these processes allows short term weather forecasting and long term climate prediction; both are crucial for industry, government and society to plan and adapt their environments. Fluid flows, and their interactions with structures, are also important to the performance of an array of processes and products that we take for granted in our everyday lives: gas and water flow to our homes, generation of electricity, fuel efficiency of vehicles, the comfort of our workplaces, the diagnosis and treatment of diseases, and the manufacture of most of the goods that we buy. Understanding, predicting and controlling Fluid Dynamics is key to reducing costs, increasing performance and enhancing the reliability of all of these processes and products. Our CDT draws on the substantial breadth and depth of our Fluid Dynamics research expertise at the University of Leeds. We will deliver an integrated MSc/PhD programme in collaboration with external partners spanning multiple sectors, including energy, transport, environment, manufacturing, consultancy, defence, computing and healthcare, who highlight their need for skilled Fluid Dynamicists. Through a combination of taught courses, team projects, professional skills training, external engagement and an in-depth PhD research project we will develop broad and deep technical expertise plus the team-working and problem-solving skills to tackle challenges in a trans-disciplinary manner. We will recruit and mentor a diverse cohort from a range of science and engineering backgrounds and provide a vibrant and cohesive training environment to facilitate peer-to-peer support. We will build strengths in mathematical modelling, computational simulation and experimental measurement, and through multi-disciplinary projects co-supervised by academics from different Schools, we will enable students to undertake a PhD project that both strengthens and moves them beyond their UG discipline. Our students will be outward facing with opportunities to undertake placements with industry partners or research organisations overseas, to participate in summer schools and study challenges and to lead outreach activities, becoming ambassadors for Fluid Dynamics. Industry and external engagement will be at the heart of the CDT: all MSc team projects will be challenges set and mentored by industry (with placements embedded); each student will have the opportunity for user engagement in their PhD project (from sponsorship, external supervision and access to facilities, to mentoring); and our partners will be actively involved in overseeing our strategic direction, management and professional training. Many components will be provided by or with our partners, including research software engineering, responsible innovation, commercial awareness and leadership.

Brazing is an important process for joining materials. It is quick and permits high strength, and is unique among high-temperature permanent joining methods in leaving the materials being joined largely unchanged; hence it can make complex joints and join dissimilar and difficult to weld materials (e.g. metals to ceramics and high Al/Ti content nickel superalloys respectively). It works by having a specific alloy, called a Brazing Filler Metal (BFM), introduced between the parts to be joined. Thermal treatment of the assembly is used to melt and solidify the BFM, forming a bond. These BFMs are designed specifically for different types of bonding situation, and can have many different compositions. Brazing is a key technology for many advanced applications, including the aerospace and nuclear sectors, but it has limitations. As the service requirements become more demanding, and base metals are refined, new BFMs must be developed. Some specific problems facing brazing technology today include: 1) Widening the spectrum of materials that can be joined (including higher temperature materials, bonding metals to ceramics, and also lower process temperatures for materials that cannot survive those of existing brazing alloys; functional ceramics and high strength 7000 series aluminium alloys, for example), would open up a whole host of novel technologies, using both existing and advanced materials in new ways 2) High temperature brazing uses additions such as boron or silicon to suppress the BFM melting point. They do this well, but also introduce brittle intermetallic phases in the joint region, limiting mechanical performance. 3) In practice, the parameters for brazing are determined on an application-specific basis, by experimental trial and error. Greater fundamental understanding of the brazing process will render this more efficient, permitting the brazing conditions to be designed. This project builds the understanding to address such challenges. A new type of alloy, High Entropy Alloys (HEAs) has recently come to the fore for alloy design. In these alloys, similar amounts of many elements are combined, rather than the typical approach of main solvent element with small additions of other elements to adjust the properties. Some HEAs have reported properties desirable for BFMs; e.g. the ability to add large amounts of elements to control melting point or wetting and flow behaviour without inducing brittle phases, and the multicomponent nature could mediate the transition in a joint between dissimilar materials. However, the physical metallurgy of HEAs is still relatively poorly understood, and their use in brazing has only been explored to a very limited extent. In this work we are investigating systematically the design, understanding and use of HEAs as BFMs. This both adds to our fundamental understanding of this intriguing new class of alloys, and provides the knowledge and skills to permit the design of new products for industry. The data and computer models of the brazing process we will generate give the design methods and data for the development of brazing parameters, which is currently done on a case-by-case basis. The project brings together the UK academic and industrial community on brazing for the first time, and will act as a focus for brazing interest. Aided by our industrial partners we will demonstrate the outcome of this work by two example case studies of alloy development: I) Reduced cost BFM for aero engines; current alloys contain significant amounts of Au and so a noble metal-free BFM, with appropriate performance, would reduce costs. II) Fusion BFM; to build advanced fusion reactor designs, it is necessary to join tungsten blocks on the reactor interior to copper pipes for coolant. This is currently done with BFMs with melting points <325degC; this limits operating temperatures. A new BFM would improve the performance and give more design flexibility for fusion reactor components.

Fusion is the process that powers the Sun, and if it can be reproduced here on Earth it would solve one of the biggest challenges facing humanity - plentiful, safe, sustainable power to the grid. For fusion to occur requires the deuterium and tritium (DT) mix of fuels to be heated to ten times the temperature at the centre of the Sun, and confined for sufficient time at sufficient density. The fuel is then in the plasma state - a form of ionised gas. Our CDT explores two approaches to creating the fusion conditions in the plasma: (1) magnetic confinement fusion which holds the fuel by magnetic fields at relatively low density for relatively long times in a chamber called a tokamak, and (2) inertial confinement fusion which holds the fuel for a very short time related to the plasma inertia but at huge densities which are achieved by powerful lasers focused onto a solid DT pellet. A main driver for our CDT is the people that are required as we approach the final stages towards the commercialisation of fusion energy. This requires high calibre researchers to be internationally competitive and win time on the new generation of fusion facilities such as the 15Bn Euro ITER international tokamak under construction in the South of France, and the range of new high power laser facilities across Europe and beyond (e.g. NIF in the US). ITER, for example, will produce ten times more fusion power than that used to heat the plasma to fusion conditions, to answer the final physics questions and most technology questions to enable the design of the first demonstration reactors. Fusion integrates many research areas. Our CDT trains across plasma physics and materials strands, giving students depth of knowledge in their chosen strand, but also breadth across both to instil an understanding of how the two are closely coupled in a fusion device. Training in advanced instrumentation and microscopy is required to understand how materials and plasmas behave (and interact) in the extreme fusion conditions. Advanced computing cuts across materials science and plasma physics, so high performance computing is embedded in our taught programme and several PhD research projects. Fusion requires advances in technology as well as scientific research. We focus on areas that link to our core interests of materials and plasmas, such as the negative ion sources required for the large neutral beam heating systems or the design of the divertor components to handle high heat loads. Our students have access to world-class facilities that enhance the local infrastructure of the partner universities. The Central Laser Facility and Orion laser at AWE, for example, provide an important UK capability, while LMJ, XFEL and the ELI suite of laser facilities offer opportunities for high impact research to establish track records. In materials, we have access to the National Ion Beam Centre, including Dalton Cumbria Facility; the Materials Research Facility at Culham for studying radioactive samples; the emerging capability of the Royce institute, and the Jules Horowitz reactor for neutron irradiation experiments in the near future. The JET and MAST-U tokamaks at Culham are key for plasma physics and materials science. MAST-U is returning to experiments following a £55M upgrade, while JET is preparing for record- breaking fusion experiments with DT. Overseas, we have an MoU with the Korean national fusion institute (NFRI) to collaborate on materials research and on their superconducting tokamak, KSTAR. The latter provides important experience for our students as both the JT-60SA tokamak (under construction in Japan as an EU-Japan collaboration) and ITER will have superconducting magnets, and plays to the strengths of our superconducting materials capability at Durham and Oxford. These opportunities together provide an excellent training environment and create a high impact arena with strong international visibility for our students.