Aluminium Alloys For Hydrogen Economy

International researcher team develops scalable aluminium alloys for the hydrogen economy

To the point

• Novel alloy design for aluminum: Researchers mix scandium with aluminum alloys to achieve 40 percent higher strength and five times higher resistance to hydrogen embrittlement - while maintaining the same ductility.
• Tuning the microstructure: Nanoparticles with a shell of particles out of aluminum, magnesium and scandium trap hydrogen and reduce the risk of embrittlement, while nanoparticles of aluminum and scandium increase strength.
• Industrial applicability: The strong and hydrogen-resistant alloys have already been produced under almost industrial conditions.

Aluminium alloys are well-known for their low weight and corrosion resistance, making them ideal candidates for applications in a low-carbon economy - from lightweight automobiles to tanks for storing green hydrogen. However, their widespread application is limited by a key challenge: they suffer from embrittlement leading to cracking and failure when exposed to hydrogen. Till now, alloys resistant to hydrogen embrittlement were rather soft, limiting their application in hydrogen-related technologies that require high strength. Now, researchers from the Max Planck Institute for Sustainable Materials in Germany, together with partners from China and Japan, have developed a new alloy design strategy that overcomes this dilemma. Their approach enables both exceptional strength and superior resistance to hydrogen embrittlement, paving the way for safer and more efficient aluminium components in the hydrogen economy. They have published their results in the journal Nature.

Dual nanoprecipitates trap hydrogen and boost strength

At the heart of the breakthrough is a complex, size-sieved precipitation strategy in scandium-added aluminium-magnesium alloys. Through a two-step heat treatment, the researchers engineered fine Al₃Sc nanoprecipitates on which a shell of a highly structurally complex Al₃(Mg,Sc)₂ forms in-situ. These dual nanoprecipitates are distributed throughout the alloy to serve two key roles: the Al₃(Mg,Sc)₂ phase traps hydrogen and enhances resistance against hydrogen embrittlement, while the fine Al₃Sc particles boost strength. "Our new design strategy solves this typical trade-off. We no longer have to choose between high strength and hydrogen resistance - this alloy delivers both", says Baptiste Gault, group leader at the Max Planck Institute for Sustainable Materials.

The results are compelling: a 40 percent increase in strength and a five-fold improvement in hydrogen embrittlement resistance compared to scandium-free alloys. The material even achieves a record uniform tensile elongation in hydrogen-charged aluminium alloys at even relatively high hydrogen loading - an indicator of excellent ductility under hydrogen exposure. Atom probe tomography measurements carried out at the Max Planck Institute for Sustainable Materials were essential in verifying the role of the Al₃(Mg,Sc)₂ phase in hydrogen trapping at the atomic level, offering insights into how the alloy design works on a fundamental scale. Experiments carried out at the partner institutes included electron microscopy and simulation.

From lab to industry

The researchers tested their approach across various Al alloy systems, and also demonstrated scalability by using water-cooled copper mould casting and thermomechanical processing methods that align with current industrial standards. This research lays the groundwork for a new generation of aluminium materials tailored for the demands of a hydrogen-powered future - safe, strong, and ready for industrial use.

This work was jointly carried out mainly by researchers from the Xi'an Jiaotong University (China), the Shanghai Jiao Tong University (China) and at the Max Planck Institute for Sustainable Materials (Germany).

Yasmin Ahmed Salem