We propose a novel multi-disciplinary approach for the optimisation of light alloys for structural applications in the objective of weight savings and reduction of greenhouse gas emissions for transportation applications. This approach will combine advanced experimental investigations in the fields of physical metallurgy and materials electrochemistry and the development of a mesoscopic modelling tool, and will be applied to precipitation-hardening Aluminium alloys. The development of nano-scale, multi-phase precipitate microstructures will be quantitatively characterised by advanced experimental techniques, including time-resolved synchrotron X-ray scattering, nuclear magnetic resonance, atom probe tomography and electron microscopy. It will be modelled by a physically-based approach, going well beyond the state-of-the-art by addressing the complexity of the sequence of metastable phases and of the competitive formation of multiple phases in multi-constituent alloys. The project will be carried out first on a model Al-Cu-Sn alloy and then applied on industrial alloys. The project will be carried out in two institutions that are world leading in their respective fields of physical metallurgy and design of light alloys. It will involve active training of the main researcher on multi-disciplinary experimental research tools, on modelling of phase transformations in metals, and on research administration. The project will improve the excellence of the return host (Grenoble Institute of Technology) in the field of light alloy research, improve its international links and recognition, and will impact Europe’s capabilities in the design and production of high performance light alloys. The project will improve the prospects of the main researcher to reach a prominent academic position in his field of research and teaching.