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This work assesses how powder-state evolution during reuse and ultrasonic plasma atomization affects functional behavior and environmental performance of NiTi powders.

February 12, 2026Sustainability2 citationsOpen Access

Sustainable Pathways in Powder Reuse: A Comparative Study of Virgin, Reused, and Ultrasonic-Atomization-Recycled NiTi Powder for Additive Manufacturing

HBHarsh K. BajajUniversity of Toledo MSMahyar SojoodiUniversity of Toledo FBFrancis Y. Asare BaffourUniversity of Toledo

Key Points

This work assesses how powder-state evolution during reuse and ultrasonic plasma atomization affects functional behavior and environmental performance of NiTi powders.
Systematic characterization of virgin, reused, and UPA-recycled NiTi powders
Analysis included particle-size distribution, SEM morphology, oxygen content, and differential scanning calorimetry
Life-cycle assessment from cradle-to-gate for energy demand and emissions
Reused powder offered reduced energy demand but showed degradation in functional properties
UPA-recycled NiTi recovered high sphericity and reduced cradle-to-gate energy by ~50%
CO2-equivalent emissions decreased by ~45% with UPA and achieved ~95% material recovery

Abstract

Nickel–titanium (NiTi) shape memory alloys offer transformative functionality for biomedical and aerospace systems, yet their adoption in additive manufacturing (AM) remains constrained by powder reactivity, compositional sensitivity, and the high energy of feedstock production. This work establishes a unified, data-driven evaluation of how powder-state evolution during reuse and ultrasonic plasma atomization (UPA) affects both functional behavior and environmental performance. Virgin, reused, and UPA-recycled NiTi powders were systematically characterized based on particle-size distribution (PSD), SEM morphology, sphericity, oxygen content (ONH), and differential scanning calorimetry (DSC), and these results were coupled with a process-level life-cycle assessment (LCA) spanning cradle-to-gate feedstock generation. Reused powder showed finer but broadened PSD, surface oxidation, and elevated transformation temperatures; these degradation mechanisms limited its reuse despite reducing energy demand by ~30% relative to virgin powder. UPA provided a more effective regeneration pathway: UPA-recycled NiTi recovered high sphericity and smooth particle surfaces while lowering cradle-to-gate energy from 100 ± 10 to 50 ± 5 MJ·kg−1 (≈50%) and reducing CO2-equivalent emissions by ≈45%, with ~95% material recovery. Although the UPA condition exhibited a higher oxygen content in this study due to system-level atmosphere limitations, prior work indicates that optimized inert-gas control can suppress oxidation, suggesting clear avenues for improvement. Sustainability Index analysis confirmed UPA as the most favorable route, integrating reductions in energy demand and emissions with recovery of powder morphology and reconditioning of thermal transformation behavior. More broadly, the ability of UPA to promote compositional and microstructural redistribution highlights its potential to deliberately re-tune or “reprogram” transformation temperatures for application-specific requirements when alloying and processing atmospheres are carefully managed.

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