Decarbonisation of Al alloy production by next generation recirculation approaches
Primary aluminium manufacturing is directly responsible for 2% of global CO2 emissions while recirculation of secondary aluminium can avoid >90% of these emissions. Unfortunately recycling and recirculation of aluminium alloys is hindered by the progressive accumulation of impurities in the aluminium every time the material undergoes a recirculation step. The build-up of Fe and other “tramp” elements leads to the formation of new, harmful phases in the alloy – and a progressive reduction of final mechanical properties. The basis for recirculated alloys can comprise high quality manufacturing surplus, well-sorted automotive end-of-life material, or largely undifferentiated domestic scrap, with the scientific and engineering challenges for recirculation progressively increasing. In every case, simply diluting out impurities by adding energy/carbon intensive refined primary Al is increasingly unsustainable. The recirculation process always involves a melting and casting step and it is here that the harmful elements entrained in the scrap react to form embrittling and corrosive phases. This project will research and directly visualise the dynamics of how the harmful elements form these phases and with this understanding, we will prevent their damaging effect by contriving the impurities into less harmful phases, by considering both nucleation and growth steps, and so make the recirculation process more tolerant. We have already established a suite of tools for this research including X-ray imaging, AI/ML based image analysis algorithms, phase selection modelling, comprehensive correlated microstructural analysis techniques, and mechanical testing. The project will consider both in-house cast model alloys and industry supplied recycled alloy feedstocks of different types. The research also offers collaboration opportunities with partners in Europe and North America.
The project and successful applicant may be eligible for partial or full funding from an industry partner.
