Development of strong, formable, stainless and low-cost magnesium alloys for next generation cars

Light weighting is one of the biggest challenges facing manufacturers today and urgently required for next generation cars to increase fuel efficiency and reduce carbon emissions. Reducing a car's weight by 50 kg decreases emissions by up to 5g CO2/km and increases fuel economy by up to 2%. Being 75% and 33% lighter than steel and aluminium (Al), Mg is becoming more popular with automotive engineers. In theory, Mg alloys offer a promising solution for lightweighting in several industrial sectors. However, Mg components currently only constitute ~1% of a typical car's weight. This is attributed to long-standing issues with Mg alloys such as high production cost, low formability and high corrosion rate, compared to heavier Al and steels. Therefore, designing high performance and low cost Mg alloys is in great demand for automotive industry.

Producing strong, formable, stainless and low-cost Mg alloys is recognised to be extremely difficult and has not to date been achieved. Traditional alloy design routes and manufacturing processing are not only time-consuming and not cost-effective, but also cannot guarantee production Mg alloys with high performance. In addition, the highly debated recrystallisation and deformation mechanisms, critical in optimising mechanical and physical properties of Mg alloys, need to be thoroughly explored and established.

The overall objective of this fellowship is to develop new routes of alloy design, simultaneously developing innovative manufacturing processes, thereby producing strong, formable, stainless and low-cost Mg alloys(e.g., yield strength >300 MPa, Index Erichsen (I.E.) value indicating stretch formability >8mm, corrosion rate <0.4mg/cm2/day). This will be achieved by understanding how the alloying elements interact with each other and how the developed processes can be used to tailor multi-scale microstructures (e.g., alloys containing ultrafine grains (~1 microns) with weak texture). Equipped with vast state-of-the-art facilities covering alloying designing, manufacturing and processing, testing and characterisation, Royce@Sheffield and Sorby Centre will help me deliver a step change in the discovery and development of new Mg alloy systems, enabling concepts development from early, fundamental research right through to translation to industry and, crucially, covering Technology Readiness Levels (TRL) 1 to 6.

Recently, a corrosion-resistant Mg-Li alloy was produced, but its high production cost and potential flammability still need to be considered before it can be commercially adopted. My goal is to push the boundaries of high-performance light Mg alloys yet further and I already have evidence that I can increase the strength and corrosion resistance of a commercial Mg alloy, currently approved by U.S. Federal Aviation Administration, without ductility loss using novel thermomechanical processing. This fellowship will address significant challenges in coupling high mechanical properties and corrosion resistance within a single alloy system.

The fellowship aims to help industrial project partners accelerate the development of new advanced light alloys. New thermomechanical/manufacturing processes are exportable technology and will permit companies to develop new IP. My research will be further extended to develop products for aerospace, public transport and medical industries and ensure a low carbon economy in the UK. Most importantly, this fellowship will assemble a new UK team of engineering and microscopists with the aim of turning vulnerable Mg into reliable structural/medical materials, thereby accelerating the pace of light weighting in several industrial sectors.

The main outcomes of this fellowship will be alloy designing strategies and novel low-cost processing for Mg alloys. These are core themes in metallurgy and manufacturing and undoubtedly can be applied to other metal and alloy systems. The fellowship outputs therefore will inspire relevant engineers working in light weighting projects distributed in several industry sectors (e.g., transport, aerospace, defence, healthcare, and manufacturing) to address challenges (Clean Growth Mission: Establish the world's first net-zero carbon industrial cluster by 2040 and at least 1 low-carbon cluster by 2030) and accelerate research progress in their R&D departments. For example, Department of Materials Science and Engineering (MSE) in the University of Sheffield works closely with VW and Bentley and the designed high performance alloys will make the automobile makers consider embedding more light Mg alloys into cars to increase their competitiveness in the market and contribute low carbon economy. The UoS has strong links with aero industry via AMRC and can explore industry collaborations with Airbus and Boeing to produce light weighting components. For example, the buy-to-fly ratio of metallic materials can be increased with low-cost light alloy systems and novel cost-effective processing developing these alloys. Most importantly, developing innovative manufacturing and advanced materials associated with the cost-effective decarbonisation will consolidate the UK's prime position at the forefront of the global shift to Clean Growth.

My two industrial project partners will contribute considerable staff time to participate in project annual meetings and support some research activities in their own labs. They will be the first beneficiaries to access our most updated original and research findings and could help them adjust their R&D research areas and investment. In addition, throughout this fellowship, the industrial project partners will gain new knowledge and have a deep understanding of microstructure evolution during processing and how to tailor properties of alloys. This will help industrial project partners to accelerate the development of new low-cost light alloy systems to meet the demand in market and become the main supplier globally. The developed novel thermomechanical/manufacturing processes can be potentially exportable technology as companies develop new IP and the new alloys could also be patented, which will increase the income of companies.

The commercial software suppliers, open source toolbox developers and their users will benefit from the large data, new/modified programme scripts generated during this fellowship when my team use these software and toolboxes for data analysis. The data associated with novel Mg alloys could complement their existing databases, extend their applications to other alloys systems and enhance their research capacity and skills.

In the long term, this project will impact all human beings by reducing carbon emissions resulting from light weighting. Cars with reduced weight can increase fuel/battery efficiency and reduce our travelling cost. Identifying suitable elements to replace rare earth (RE) elements for developing high performance Mg alloys will delay the depletion of strategic RE elements and maintain sustainable development of our society. In addition, avoiding RE elements will reduce significant pollution issues during extracting RE elements from mines and, thereby creating an environmentally friendly life pattern. The Mg alloys can be designed purposely as biomaterials for specific groups of patients. For example, the alloys can be developed into harmless and biodegradable implants (e.g., stents and bone fixation screws) working with healthcare companies. No secondary operation is required to take out the Mg implants from patients' bodies. All these approaches will increase environmental sustainability and benefit the quality of life for the general public.