Speaker
Description
Abstract: Environmentally assisted embrittlement of high-strength Al alloys hinders their wide applications. The important role of hydrogen (H) associated with the H “embrittlement” mechanism occurs. However, the challenge of assessing the precise trapping sites of H makes the mechanisms remain ambiguous. In this presentation, I discuss the findings on H associated with specific microstructural features in a high-strength 7xxx Al alloy [1] investigated using atom probe tomography. We successfully achieved visualization and assessment of H at second-phases and grain boundaries, with the enrichment of one order of magnitude higher as opposed to the Al matrix. We used these observations to guide atomistic ab initio calculations, which show that the co-segregation of alloying elements and H favours grain boundary decohesion, and the strong partitioning of H into the second-phase particles removes solute H from the matrix, hence preventing H embrittlement. In the second part [2], I talk about the recent results regarding direct evidence that the oxide acts as a trap for H, pointing at the essential role of the Al oxide might act as a kinetic barrier in preventing H embrittlement. These insights further advance the mechanistic understanding of H-assisted embrittlement in Al alloys, emphasizing the role of H traps in minimizing cracking and guiding new alloy design.
Keywords: Hydrogen embrittlement, 7xxx Al alloy, Mechanical properties, Atom probe tomography, Ab-initio calculations
References:
[1]. H. Zhao, P. Chakraborty, D. Ponge, T. Hickel, B. Sun, C. Wu, B. Gault, D. Raabe, Hydrogen trapping and embrittlement in high-strength Al alloys. Nature 602, 437-441, (2022).
[2]. H. Zhao, Y. Yin, Y. Wu, S. Zhang, A. Mingers, D. Ponge, B. Gault, M. Rohwerder, D. Raabe, How solute atoms control aqueous corrosion of Al alloys, Nature Communications, 15, 561, (2024).
