| Abstract Scope |
We report progress on recycling three high-priority material streams: rare-earth permanent magnets, copper, and nickel. For sintered NdFeB hard magnets, hydrogen-decrepitation routes selectively break down the microstructure while preserving coercivity and remanence relative to reference material. For copper, we map the relationship between scrap chemistry, impurity partitioning during melt practice, electrical conductivity, and downstream forming constraints, identifying processing windows where upgrading rather than downcycling becomes feasible. For nickel, hydrogen-plasma and solid-state co-reduction pathways are compared against carbothermic benchmarks, with quantitative assessment of greenhouse-gas intensity, impurity tolerance, and property retention in Ni-rich alloys. Across all three systems, theory, atom probe tomography and correlative electron microscopy reveal how residual tramp elements segregate and partition to grain boundaries, hetero-interfaces, and precipitates, governing functional performance. These findings establish microstructure-centered recycling as a scientifically tractable and industrially scalable approach to closing critical-element loops. |