Powder reuse in powder bed fusion-laser beam of WE43 magnesium alloy: towards sustainable manufacturing of biodegradable implants

Magnesium alloy WE43 is desirable for biomedical implants due to its biocompatibility, degradability, and mechanical properties closely matching those of natural bone. Processing of WE43 by additive manufacturing (AM), such as powder bed fusion laser beam (PBF-LB), can further its potential for biomedical applications through improved customization (i.e., patient-specific implants) and fabrication of complex geometries. Nevertheless, AM-fabricated Mg implants have yet to reach clinical implementation. To enable this transition, while contributing to the global drive for more sustainable manufacturing, the aim of this research was to investigate the effect of powder reuse during PBF-LB processing of WE43. Specifically, we focus on the influence on both powder properties as well as bulk density and mechanical properties of printed components. Results indicate that repeated reuse alters the powder's morphology and particle size distribution (PSD), through the formation of satellites and agglomerates, along with a preferential consumption of smaller particles (< 20 μm) during processing. In turn, powder flowability was increased, but both spreadability and layer density decreased. Only minor compositional changes were observed in both powders and printed samples. Despite these changes in the powder feedstock, the effect on the density of printed samples was minimal, as only small variations in porosity were observed between the initial (0.43%) and final printing cycles (0.61%), thereby resulting in a limited effect on sample hardness. The impact on sample density remained minimal despite introducing out-of-spec powder to the feedstock as a worst-case scenario. These findings demonstrate the potential for reducing material wastage when processing biomedical alloy WE43 by PBF-LB and can be used to support powder handling recommendations to ensure quality and sustainability for future commercial applications. • Reuse leads to loss of fine and coarse particles, reduced sphericity, and increased irregularity and porosity. • Overall composition remains stable, but increased oxides suggests gradual oxidation. • Printed parts maintain >99% density and consistent hardness, even with high reused powder ratios. • PBF-LB reliably produces high-quality parts despite powder degradation over multiple reuse cycles.