Development of innovative and tailored aluminium alloys with low criticality issues for sustainable mobility

The aluminium casting industry plays a crucial role in modern manufacturing, particularly in the automotive sector, where lightweight and high-performance components are essential. Within the European Union, the transition toward a circular economy has intensified the need for sustainable material solutions. Aluminium alloys are key enablers due to their recyclability and mechanical performance; however, the classification of aluminium and its major alloying elements such as silicon and magnesium as Critical Raw Materials (CRMs) imposes new constraints on alloy design and manufacturing strategies. This doctoral thesis proposes and validates a sustainability-oriented methodology for developing high-performance aluminium alloys with reduced CRM content, enhanced High Pressure Die Casting (HPDC) processability, and suitability for automotive structural components. The approach integrates criticality assessment, castability evaluation, thermodynamic modelling, experimental validation, and life cycle assessment to establish a link between resource efficiency and industrial feasibility. A multi-criteria framework was developed to assess raw material criticality based on factors such as elemental abundance, geopolitical and environmental risks, supply risk, economic importance, and recycling rates. Castability was evaluated considering fluidity, shrinkage, die soldering, hot tearing, and sludge/dross formation. This integrated framework supports informed alloy design decisions under increasing regulatory and supply chain pressures. Using this methodology, four new secondary aluminium alloys with reduced criticality were developed within the framework of the SALEMA project, targeting Body-in-White components (shock tower and frontal frame). Thermodynamic simulations using the CALPHAD approach (Thermo-Calc®) enabled optimisation of compositions prior to laboratory casting trials. Mechanical performance and microstructure were evaluated after T5 heat treatment, and the optimal alloy was validated at industrial scale through HPDC demonstrators. All developed alloys met the required mechanical properties (YS and UTS) for the targeted components, providing viable alternatives to conventional high-CRM alloys such as AlSi10MnMg The environmental performance of aluminium casting was further analysed through life cycle assessment, focusing on embodied energy and carbon footprint. Different melting technologies (crucible, induction, reverberatory electric and gas furnaces) were compared for primary and secondary routes under varying return rates. Results indicate that sustainability requires a combined optimisation of alloy design, process efficiency, and energy source, with electricity-based furnaces offering the most favourable environmental performance. Overall, this research demonstrates that high mechanical performance, reduced CRM dependency, and improved environmental sustainability can be achieved through an integrated alloy and process design strategy, providing a practical framework for circular and resource-resilient aluminium casting in automotive applications.