Nature‐Inspired Incorporation of Precipitants into High‐Strength Bulk Aluminum Alloys Enables Life‐Long Extraordinary Corrosion Resistance in Diverse Aqueous Environments

Abstract

AbstractThe safe service and wide applications of lightweight high‐strength aluminum alloys are seriously challenged by diverse environmental corrosion, since high strength and corrosion resistance are mutually exclusive for metals while surface protection cannot provide life‐long corrosion resistance. Here, inspired by fish secreting slime from glands to resist external changes, a strategy of incorporating precipitants as the slime into bulk metals using the inner cavity of opened carbon nanotubes (CNTs) as the glands is developed to enable high‐strength aluminum alloys with life‐long superior corrosion resistance. The resulting material has ultrahigh tensile strength (≈700 MPa) and extraordinary corrosion resistance in acidic, neutral and alkaline media. Notably, it has the highest resistance to intergranular corrosion, exfoliation corrosion and stress‐corrosion cracking, compared with all previously reported aluminum alloys, and its corrosion rate is even much lower than that of corrosion‐resistant pure aluminum, which results from the pronounced surface enrichment of precipitants released (secreted) from exposed CNTs forming a protective surface film. Such high corrosion resistance is life‐long and self‐healing due to the on‐demand minimal self‐supply of the precipitants dispersed throughout the bulk material. This strategy can be readily expanded to other aluminum alloys, and could pave the way for developing corrosion‐resistant high‐strength metallic materials.