A New Class of Ultra-High-Strength, Corrosion-Resistant, and Recyclable Aluminum Alloys

Aluminum alloys offer an excellent strength-to-weight ratio and are therefore widely used in automotive, aerospace, and marine applications. However, their broader adoption is limited by two factors: (1) a decline in corrosion performance as strength is increased, and (2) the maximum achievable strength of commercial Al alloys being restricted to ~600 MPa. Developing Al alloys with ultra-high strength (yield strength >1 GPa) while retaining superior corrosion resistance would enable the next generation of lightweight and environmentally friendly structural materials. This research demonstrates that such ultra-high-strength, corrosion-resistant Al alloys can be achieved through appropriate alloying strategies combined with advanced processing methods. Alloys produced via mechanical alloying of Al with selected elements (including Si, Cr, Mo, Nb, Fe, Ni, V, and Ti) exhibit remarkably high pitting potentials along with exceptional strength. Several compositions showed no measurable corrosion even after immersion in 0.1 M NaCl solution for six months, and the repassivation potentials of these alloys were significantly elevated. The consistently high corrosion resistance and strength observed across a broad compositional space indicate excellent compositional tolerance, which in turn suggests strong potential for improving the recyclability of high-performance Al alloys. The mechanisms governing the observed corrosion resistance and strength, as well as the alloy design principles enabling these properties, will be discussed.