Two-Month In Vitro Degradation of 3D-Printed Biodegradable FeMnC Alloys for Biomedical Applications

Over the last decade, Fe-Mn-based bioresorbable implants have attracted significant interest due to their outstanding mechanical properties, including ductility and strength, and their ability to degrade over medium-to-long healing periods, eliminating the need for secondary surgeries for implant removal. However, their slow degradation under physiological conditions limits their practical use, especially for short-term degradable implants. Additive manufacturing facilitates rapid production with tailored compositions, offering advantages over traditional casting methods. Yet, the structure, the microstructure, the degradation behavior, and the mechanical properties are known to be impacted by the fabrication methods. In this context, this study investigates the degradation behavior of 3D-printed FeMnC alloys produced via laser powder bed fusion using volumetric energy densities from 75 J/mm³ to 87 J/mm³. Microstructure and degradation rate relationships were explored through microstructural characterization (SEM, XRD, EBSD) and static immersion tests in modified Hanks' solution over 60 days. XRD confirmed a fully austenitic microstructure in all conditions, while SEM and EBSD revealed refined structures along the building direction. The alloy printed at 87 J/mm³ exhibited the lowest degradation rate for both immersion periods, with values near 0.04 mm/year after 14 days and 0.03 mm/year after 60 days.