Structurally complex phase engineering enables hydrogen-tolerant Al alloys.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40307552.
- Also identified by DOI 10.1038/s41586-025-08879-2 and PMC identifier 12058518.
- Licence recorded as CC BY-NC-ND.
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Abstract
Hydrogen embrittlement (HE) impairs the durability of aluminium (Al) alloys and hinders their use in a hydrogen economy<sup>1-3</sup>. Intermetallic compound particles in Al alloys can trap hydrogen and mitigate HE<sup>4</sup>, but these particles usually form in a low number density compared with conventional strengthening nanoprecipitates. Here we report a size-sieved complex precipitation in Sc-added Al-Mg alloys to achieve a high-density dispersion of both fine Al<sub>3</sub>Sc nanoprecipitates and in situ formed core-shell Al<sub>3</sub>(Mg, Sc)<sub>2</sub>/Al<sub>3</sub>Sc nanophases with high hydrogen-trapping ability. The two-step heat treatment induces heterogeneous nucleation of the Samson-phase Al<sub>3</sub>(Mg, Sc)<sub>2</sub> on the surface of Al<sub>3</sub>Sc nanoprecipitates that are only above 10 nm in size. The size dependence is associated with Al<sub>3</sub>Sc nanoprecipitate incoherency, which leads to local segregation of magnesium and triggers the formation of Al<sub>3</sub>(Mg, Sc)<sub>2</sub>. The tailored distribution of dual nanoprecipitates in our Al-Mg-Sc alloy provides about a 40% increase in strength and nearly five times improved HE resistance compared with the Sc-free alloy, reaching a record tensile uniform elongation in Al alloys charged with H up to 7 ppmw. We apply this strategy to other Al-Mg-based alloys, such as Al-Mg-Ti-Zr, Al-Mg-Cu-Sc and Al-Mg-Zn-Sc alloys. Our work showcases a possible route to increase hydrogen resistance in high-strength Al alloys and could be readily adapted to large-scale industrial production.