This project is to exploit the commercial application of the novel Twin Screw Rheo-Extrusion (TSRE) technology and facilitate the related technology transfer to industry. The TSRE process takes advantage of the non-dendritc microstructure and dynamic shear resistance of semisolid-metal slurries and produces simple metal profiles directly from the melt, with designed microstructure, uniform chemistry and excellent properties. This offers a step change for metal production, presenting a major opportunity for the UK industry to save costs and energy and enhance efficiency. The project's core objective is to successfully demonstrate the TSRE process for producing aluminium welding rods/wires at an industrial-scale.

The creation of new, 21st Century manufactured products gives us exciting possibilities. However, the number of complex devices and components that consist of one piece of a single material is negligible; almost all manufacturing involves the joining of materials. Joining technology is extensive, but is still challenged by novel designs and new advanced materials. Frequently, these needs could be met by soldering, where a low melting point alloy is introduced in liquid form into the joint, where it solidifies, making a bond. Many people will associate soldering with the electronics industry, where it is widely used, reliably, effectively and at low cost. Yet current soldering is not good at forming bonds with many materials, (for example metals with tenacious oxides and ceramics) and it does not form strong joints which can resist exposure to elevated temperatures where applications demand it. To do this may need an approach used for brazing (very much like soldering, but at higher temperature) of adding an element to the alloy, whose role is to chemically interact with surfaces and improve wetting when liquid and bonding once solidified. Adapting the terminology from brazing, this would be "active soldering". Such a process is not simple however. First we must identify the correct active elements, which may not be the ones used in brazing. These must produce sufficient reaction at low temperatures and be adapted to the materials being bonded. Secondly, a way to introduce a large enough amount of these elements into the solder is required. Solders are based on tin, which may react with the active elements itself if too large quantities are present. Finally, such joints that have been attempted have very poor mechanical properties, and these must be improved. To resolve these challenges, we will deposit the active elements (selected with the aid of thermodynamic modelling) onto a metallic carrier, a Ni or Cu sponge or foam, with fine (~0.5mm) pores, and infiltrate the Sn into this, creating a composite solder. This will keep the active elements and the Sn separate until soldering, when the Sn will begin to dissolve the foam and progressively release the active material to aid in bonding. The residual network of the foam structure across the joint seam will also be effective in increasing the joint strength. We will make and test these composite solders and the joints, and we will also probe the reactions occurring in great detail, to ensure we understand the key step of this new technology. Of immediate use, this approach will improve the strength of bonds achieved in current applications (such as in antennae, heat exchangers and semiconductor devices), give them higher temperature resistance in service and reduce the environmental impact of the process, by removing the need for polluting chemical fluxes or electroplating to prepare the joint and aid bonding. The benefits certainly do not stop there, as the technology would also allow new applications. For example, metals like stainless steel are brazed in vacuum at high temperature; achieving the same goal at lower temperatures and in air would be a much less expensive process. Low process temperatures save energy and cost; for example, some electroceramics (important for, e.g. capacitors) can be processed by cold sintering at temperatures as low as 200degC, but the advantages would be lost without low temperature means to join them in electronic devices. Advanced materials such as graphene also hold much promise in areas like touchscreens and circuitry, and a technique like that developed here would be an essential part of making this a reality. The simple, mass manufacturing nature of solder means that, with our research partners including end users and processors of solder materials, the scalability of the new method created, and the chances of realising these benefits, will be very high.

The UK metal casting industry is a key player in the global market. It adds 2.6bn/year to the UK economy, employs directly around 30,000 people and produces 1.14 billion tons of metal castings, of which 37% is for direct export (Source: CMF, UK). It underpins the competitive position of every sector of UK manufacturing across automotive, aerospace, defence, energy and general engineering. However, its 500 companies are mainly SMEs, who are often not in a position to undertake the highest quality R&D necessary for them to remain competitive in global markets. The current EPSRC IMRC portfolio does not cover this important research area nor does it address this clear, compelling business need. We propose to establish IMRC-LiME, a 3-way centre of excellence for solidification research, to fill this distinctive and clear gap in the IMRC portfolio. IMRC-LiME will build on the strong metal casting centres already established at Brunel, Oxford and Birmingham Universities and their internationally leading capabilities and expertise to undertake both fundamental and applied solidification research in close collaborations with key industrial partners across the supply chain. It will support and provide opportunities for the UK metal casting industry and its customers to move up the value chain and to improve their business competitiveness. The main research theme of IMRC-LiME is liquid metal engineering, which is defined as the treatment of liquid metals by either chemical or physical means for the purpose of enhancing heterogeneous nucleation through manipulation of the chemical and physical nature of both endogenous (naturally occurring) and exogenous (externally added) nucleating particles prior to solidification processing. A prime aim of liquid metal engineering is to produce solidified metallic materials with fine and uniform microstructure, uniform composition, minimised casting defects and hence enhanced engineering performance. Our fundamental (platform) research theme will be centred on understanding the nucleation process and developing generic techniques for nucleation control; our user-led research theme will be focused on improving casting quality through liquid metal engineering prior to various casting processes. The initial focus will be mainly on light metals with expansion in the long term to a wide range of structural metals and alloys, to eventually include aluminium, magnesium, titanium, nickel, steel and copper. In the long-term IMRC-LiME will deliver: 1) A nucleation-centred solidification science, that represents a fundamental move away from the traditional growth-focused science of solidification. 2) A portfolio of innovative solidification processing technologies, that are capable of providing high performance metallic materials with little need for solid state deformation processing, representing a paradigm shift from the current solid state deformation based materials processing to a solidification centred materials engineering. 3) An optimised metallurgical industry, in which the demand for metallic materials can be met by an efficient circulation of existing metallic materials through innovative technologies for reuse, remanufacture, direct recycling and chemical conversion with limited additions of primary metal to sustain the circulation loop. This will lead to a substantial conservation of natural resources, a reduction of energy consumption and CO2 emissions while meeting the demand for metallic materials for economic growth and wealth creation.

The production of high-value, high-quality alloys is typically within the remit of intermediate weight class (1 - 100 ton alloy weight output) continuous casting (CC) rigs which process metals from liquid to solid by cooling. CC rigs are typically limited by the types of alloys they can output owing to a chemical incompatibility between the alloy and the ceramic materials comprising the rig, or the maximum operational temperatures. To produce a single rig type which can output a wide range of alloys is not possible for these reasons, however this project shall address this representing a first of a kind offering. A partnership shall be formed between the University of Dundee (UoD) and Ruatomead Ltd, combining 40 years of metallurgy experience at RM and advanced computational models at the UoD and materials analysis to address the research challenge: how to identify the correct heat transport properties and material compatibility of a CC rig design. The following will be considered. The alloys to be processed through the developmental rig are applied in a wide range of useful, high value industries, such as power, transport and marine. In making alloy manufacturing a more efficient process this will reduce energy requirements for the casting process and can output to greater volumes alloy within these high value manufacturing areas. Computer models will provide insight into design optimisations which can be used to improve the cooling efficiency of the rig by alterations to contact surface areas and modifications to boundary flow. Alterations to the CC rig can give rise to new properties within a cast alloy owing to its solidification conditions, such as the formation of precipitate strengthening phases within Cu-Cr-Zr generated under high cooling rates produced within the proposed setup, which can produce increased tensile strength. This is of particular use in reducing the numbers of costly post-casting processing required to form useful properties in cast alloys. The alloy systems for consideration are base around copper, nickel, cobalt, aluminium steel and a newly developed material with interesting high strength properties referred to as a multicomponent alloy (Cantor, Co-Cr-Fe-Ni-Mn). The investigation of these alloys here is driven by an industrial demand such as the application of Cu-Cr-Zr for its previously mentioned strength, conductivity and corrosion resistance, which is being utilised as overhead power cabling for electric trains and to replace the current inferior Cu-Mg alloy system, for net-zero goals. Or, oxygen-free Cu rod used for its high electrical purity and conductivity in the transmission of power between wind turbines, the transmission of data within electric vehicles, or within electric motors fabrication. The partnership shall produce a developmental CC rig capable of outputting the wide range of alloys mentioned and with different forms closer to customer requirements, which historically were not cast-able from one machine type and required multiple post-casting processing. The the formation of alloy rod of diameters less than the industry standard (8 mm), is closer to customer requirements and desirable for reducing processing costs. Its application is also for use as additive manufacturing feedstock. The developed CC rig shall provide to materials scientists a facility to test new alloy forms and for interested industrial bodies, a means to develop a CC process. The partnership shall also lead to the development of an advanced computational model which will be able to predict casting conditions, to identify new solidification behaviours and to reduce the numbers of costly casting trials required for alloy casting evaluation. It will contribute to the economic development of the Dundee area and pin Dundee as a centre for alloy processing innovation.