Aluminium recycling uses just 5% of the energy needed to produce virgin metal, yet most scrap aluminium today gets down-cycled into lower-grade products rather than returned to high-performance use. This project aims to close that loop. The problem is fundamental physics: when you try to recycle high-strength aluminium alloys, the impurities and microstructural changes that occur during use make it difficult to restore the original mechanical properties. Current recycling methods cannot reliably recover the ultra-high strength needed for lightweight vehicle structures. The researchers at BCAST and Constellium will develop a new class of "STEP Al-alloys" designed from the outset to be fully recyclable without performance loss. These alloys target twice the strength of conventional aluminium, combined with good ductility and crashworthiness. If successful, the work could transform automotive manufacturing supply chains. Car makers could use lighter, stronger aluminium structures that reduce fuel consumption, while the aluminium industry could dramatically cut its carbon footprint—currently 1% of global CO₂ emissions—by relying on recycled stock rather than primary smelting. The programme also advances fundamental understanding of how precipitation and dislocations interact in metals, knowledge that could inform alloy design far beyond transport.
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As the second most widely used structural metal in the world, after steel, Al-alloys have a low density (3 times lighter than steel), high corrosion resistance and a good combination of physical and mechanical properties. In terms of specific strength (strength/density), Al-alloys outperform conventional steels and match the performance of advanced high strength steels (AHSS) developed in recent years. This makes Al alloys particularly attractive for applications in the transport industry. The demand for aluminium products has increased 30-fold since 1950 and this exceptional growth is predicted to continue well into the first half of the 21st century. However, there is both good and bad news about aluminium. The bad news is that aluminium production uses 3.5% of global electricity and causes 1% of global CO2 emissions resulting in a large negative impact on our environment; and the good news is that aluminium is in principle infinitely recyclable and its recycling requires only 5% of the energy required for primary metal production. In addition, since 1908 we have cumulatively produced over 1 billion tonnes of aluminium, and more than 75% of this aluminium still exists as accessible stock in our society. Such metal stock will become our energy "bank" and a rich resource for meeting our future needs. Our long term vision is "full aluminium circulation", in which the global demand for aluminium is met by a full circulation of secondary aluminium (with only limited addition of primary aluminium each year) through reduced usage, reuse, remanufacture, closed-loop recycling and effective recovery and refining of secondary aluminium. Under this shared vision, BCAST (a global leader in light metal research) and Constellium (a global leader in aluminium lightweight structure supply) have established a strategic research partnership for developing high performance Al-alloys and their applications in lightweight vehicle constructions, with research projects covering a wide range of technology readiness levels. Under the shared vision for full metal circulation, BCAST and Constellium have identified the shared research challenges and co-created a coherent fundamental research programme on STEP (STrain Enhanced Precipitation) Al-alloys to complement the existing applied research activities. This programme aims to strengthen the existing, strategic research partnership between Constellium and BCAST through successful execution of a co-created STEP Al research programme, which will accelerate academic research impact on business, balance capability between fundamental and applied research, and will build and consolidate the UK's internationally leading position in aluminium research. In the STEP Al programme, we will develop a new generation of high performance Al-alloys with ultra-high strength (twice the strength of their conventional counterparts), good ductility, high crashworthiness and high thermal conductivity; we will develop a novel direct chill (DC) casting process and thermomechanical processing procedures to realise the full potential of STEP Al-alloys; we will deliver new insights into the precise precipitation mechanisms and the solute-dislocation-precipitate interactions to underpin both materials and processing technology development; and we will also develop a holistic approach to the design of lightweight automotive structures to demonstrate the full potential of our research outcomes. Successful execution of the STEP Al programme will deliver significant advances in nucleation science, physical metallurgy, advanced alloy development, materials processing technologies and holistic engineering design. These will in turn have profound impact on UK productivity, the overall UK economy and our environment.
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