Dierk Raabe studied music (conservatorium Wuppertal, Germany), metallurgy and metal physics (RWTH Aachen, Germany). After his doctorate 1992 and habilitation 1997 at RWTH Aachen he received the Heisenberg fellowship award of the German Research Foundation and worked at Carnegie Mellon University (Pittsburgh) and at the National High Magnet Field Lab (Tallahassee). He joined Max Planck Society as a director in 1999. His interests are in computational materials science, phase transformation, alloy design, hydrogen, sustainable metallurgy and atom probe tomography. He received the Leibniz award (highest German Science award), 2 ERC Advanced Grants (highest European research Grant) and the Acta Materialia Gold Medal Award. He is a professor at RWTH Aachen and honorary professor at KU Leuven. He is a member of the National Academy Leopoldina.
High strength aluminium alloys are backbone structural materials for electrical vehicles, planes and spaceships. They must fulfil (at least) the following criteria: high strength, good formability, recyclability and mass producibility, and resistance to corrosion and hydrogen embrittlement[1].
The first two criteria require to design alloys with complex microstructures which introduces multiple local galvanic elements and undesired interfacial decoration phenomena that affect corrosion and hydrogen embrittlement. The sustainability criterion of making such alloys fully recyclable introduces the challenge of compositional variation and the intrusion of undesired tramp elements, both of which also influence the materials' behaviour in real environments[2].
In this presentation we discuss the specific influence of these features on hydrogen embrittlement. For this purpose, we performed atomic-scale investigations of hydrogen trapped in second-phase particles and at grain boundaries in a high-strength 7xxx Al alloy [3,4]. We used these observations to guide atomistic ab initio calculations, which show that the co-segregation of alloying elements and hydrogen favours grain boundary decohesion, and the strong partitioning of hydrogen into the second-phase particles removes solute hydrogen from the matrix, hence preventing hydrogen embrittlement. Our insights advance the mechanistic understanding of hydrogen-assisted embrittlement in Al alloys, emphasizing the role of hydrogen traps in minimizing cracking and guiding future hydrogen-resistant alloy design.
References
1. D. Raabe et al.: Making Sustainable Aluminum by Recycling Scrap: The Science of “Dirty” Alloys. Prog. Mater. Sci. 2022, 100947.
2. D. Raabe, D. et al.: Strategies for Improving the Sustainability of Structural Metals. Nature 2019, 575, pp 64–74.
3. H. Zhao et al.:Hydrogen Trapping and Embrittlement in High-Strength Al-Alloys. Nature 2022, 602, pp 437–441.
4. H. Zhao et al.: Interplay of Chemistry and Faceting at Grain Boundaries in a Model Al Alloy. Phys. Rev. Lett. 2020, 124 (10)