Hydrogen trapping and embrittlement in high-strength Al alloys
Abstract
Ever more stringent regulations on greenhouse gas emissions from transportation motivate efforts to revisit materials used for vehicles1. High-strength aluminium alloys often used in aircrafts could help reduce the weight of automobiles, but are susceptible to environmental degradation2,3. Hydrogen `embrittlement' is often indicated as the main culprit4; however, the exact mechanisms underpinning failure are not precisely known: atomic-scale analysis of H inside an alloy remains a challenge, and this prevents deploying alloy design strategies to enhance the durability of the materials. Here we performed near-atomic-scale analysis of H trapped in second-phase particles and at grain boundaries in a high-strength 7xxx Al alloy. 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. Our 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.
- Publication:
-
Nature
- Pub Date:
- February 2022
- DOI:
- 10.1038/s41586-021-04343-z
- arXiv:
- arXiv:2201.04490
- Bibcode:
- 2022Natur.602..437Z
- Keywords:
-
- Condensed Matter - Materials Science
- E-Print:
- doi:10.1038/s41586-021-04343-z