Upcycling Mixed Alloy Scraps via Liquid Metal Dealloying for Cross-Alloy Circular Economy

The challenge of mixed, contaminated metal scrap and the unsustainable environmental footprint of traditional primary metal production based on fossil reductants necessitate innovative, scalable recycling strategies. This study presents a generic liquid metal dealloying-vacuum (LMD-V) approach for synergistic upcycling of complex multiple alloy scraps, representing a paradigm shift from conventional single-stream recycling. Demonstrated using nickel (Ni) superalloy and magnesium (Mg) alloy scrap, the method leverages Mg's low melting point to extract Ni, leaving refractory metals (rhenium (Re), tungsten (W), tantalum (Ta)) as a porous residue. Vacuum treatment recovers 99.7% pure Mg and yields a brittle nickel-aluminum (Ni-Al) alloy, directly converted into Raney-Ni catalyst with commercial-grade performance. The weakened porous residue (2%-6% of its original strength) facilitates critical metal recovery. Compared to conventional recycling, it reduces energy and carbon footprints by 74.6% and 56.7%, respectively. By transforming carbon-intensive scraps into high-value products, LMD-V establishes a closed-loop, scalable pathway for mixed scrap recycling, profoundly advancing the circular economy.