ADVANCED MATERIALS & PROCESSES | MARCH 2026 20 for example, severe plastic deformation during deposition can homogenize microstructures and mitigate feedstock variability, enabling properties comparable to wrought materials. In melt-based and extrusion AM, blending strategies, feedstock reconditioning, and in-process monitoring are actively being explored to manage variability while maintaining part quality. Design considerations are also evolving alongside upcycling-enabled AM. Rather than treating feedstock variability solely as a limitation, several studies suggest that part geometry, deposition strategy, and load paths can be intentionally designed to accommodate or even exploit localized anisotropy and heterogeneity. Design- for-upcycling concepts, though still in their infancy, highlight the need to simultaneously optimize material sourcing, process selection, and compo- nent design. Together, these develop- ments indicate that performance, qualification, and design are no longer downstream concerns but integral elements shaping the viability of material upcycling across AM modalities. CASE STUDIES IN UPCYCLING-ENABLED AM Solid-state Upcycling of Machining Chips for AFSD. One of the most direct demonstrations of material upcycling for AM involves transforming metallic machining waste into feedstock for AFSD. In this approach, aluminum or other alloy chips generated during conventional machining are cleaned, compacted into dense feed rods, and subsequently deposited via AFSD in the solid state (Fig. 2). This workflow bypasses energy- intensive remelting and powder atomization while retaining alloy chemistry. Experimental studies have shown that AFSD components produced from upcycled chip-based feedstock can achieve mechanical properties comparable to those of wrought material. Microstructural refinement induced by severe plastic deformation, recovery, and recrystallization during deposition further contributes to performance improvements. From a sustainability perspective, lifecycle and techno-economic analyses indicate significant reductions in energy use, greenhouse gas emissions, and feedstock costs compared with conven- tional powder-based AM routes. The process is particularly well-suited for integration into closed-loop manufacturing cells, where machining and additive repair or fabrication coexist. Recycled Feedstocks for Melt- and Extrusion-based AM. A contrasting upcycling pathway is observed in melt- and extrusion-based AM processes, where recycled materials are reintroduced through controlled reprocessing. Examples include the reuse of stainless steel or titanium scrap to produce atomized powder for PBF systems, as well as the use of pelletized recycled polymers in large-format extrusion AM. While these routes typically involve higher energy input than solid-state methods, they benefit from compati- bility with existing AM infrastructure and qualification frameworks. Industrial demonstrations have shown that blending recycled feedstock with virgin material can maintain part quality while reducing overall material cost and environmental impact. In polymer AM, extrusion-based systems have successfully utilized post-consumer waste streams to fabricate tooling, molds, and structural components at scale. These examples point out that no single upcycling strategy fits all AM modalities. Instead, process selection depends on performance requirements, part scale, and sustainability priorities. ENVIRONMENTAL AND ECONOMIC IMPACTS Material upcycling has attracted significant attention in additive manufacturing primarily because feedstock production is often the dominant contributor to both environmental impact and part cost. Conventional routes for producing AM-grade powders and wires typically involve multiple energy- intensive steps, including melting, atomization or drawing, classification, and transport, each adding to cumulative energy consumption, greenhouse gas (GHG) emissions, and processing costs. Upcycling strategies that reduce or bypass these steps, therefore, offer compelling sustainability advantages, particularly when waste material is sourced locally and processed close to the point of use. Qualitative and quantitative studies consistently indicate that solid-state upcycling routes, such as chip-based feedstock production for AFSD, can deliver substantial reductions in energy consumption and embodied carbon by eliminating remelting and atomization altogether. Similarly, reuse and reprocessing of powders, or the use Fig. 2 — Process flow from machining chips to compacted feed rod to AFSD-deposited part.
RkJQdWJsaXNoZXIy MTYyMzk3NQ==