Crossover alloys are taking the market by storm: At the Montanuniversität Leoben, a novel concept for aluminium alloys has been developed that resolves a long-standing trade-off in materials engineering: until now, aluminium materials were either easy to work with or particularly strong. These so-called crossover alloys now combine both properties in a single material.

Conventional 5xxx-series aluminium-magnesium alloys are easy to form and corrosion-resistant, but achieve only limited strength. High-strength 7xxx-series alloys, on the other hand, are significantly more difficult to process. The crossover concept developed in Leoben deliberately transcends these previously rigid class boundaries, thereby opening up new material combinations. “We haven’t simply developed a better 5xxx or a better 7xxx alloy. We asked why this boundary needs to exist at all,” explains Professor Stefan Pogatscher from the Chair of Non-Ferrous Metallurgy at the Montanuniversität Leoben. “The T-phase makes all the difference.”

The key to the performance of the new alloys lies in what is known as the T-phase. The targeted combination of magnesium, zinc and, in some cases, copper results in materials that are initially easy to form. It is only through a final heat treatment that they develop high strengths which can rival those of classic 7xxx-series alloys. A particularly efficient aspect is that the necessary hardening can be integrated into existing industrial processes, such as the paint curing process in the automotive industry. This means that no additional energy-intensive process steps are required.

From the Christian Doppler Laboratory to production

The development of the crossover alloys began at the Montanuniversität Leoben and was, from the outset, a key focus of the Christian Doppler Laboratory for Advanced Aluminium Alloys. Together with the corporate partner AMAG Austria Metall AG, one of Europe’s largest single-site aluminium recyclers, work was carried out to transfer the concept from initial laboratory samples to industrial production. What began as laboratory samples weighing around 100 grams gradually developed into larger test batches, industrial production trials at the AMAG plant in Ranshofen and, finally, prototype components. Today, the innovation – AMAG CrossAlloy®57 – is already commercially available. “Scientific validation is important. However, the decisive step is when an idea becomes a material that can be produced industrially.”