Selective laser melted Fe-30Mn-6Cu alloy: A multifunctional candidate for MRI-compatible, biodegradable, antibacterial, and biocompatible orthopedic implants

Abstract

The orthopedic potential of biodegradable iron (Fe)-manganese (Mn)-copper (Cu) alloys remains insufficiently defined, necessitating comprehensive investigation into their mechanical properties, wear resistance, magnetic resonance imaging compatibility, biodegradation behavior, antibacterial efficacy, cytocompatibility, and osteogenic differentiation capacity. This study systematically addresses these aspects through microstructural characterization, mechanical testing, and biological evaluations of Fe-30Mn-6Cu alloy fabricated via selective laser melting (SLM). For comparison, a Cu-free Fe-30Mn alloy was fabricated under similar SLM conditions. The incorporation of 6 wt.% Cu into Fe-30Mn stabilized the γ-austenite phase, enhanced yield strength, improved wear resistance, accelerated electrochemical biodegradation, and imparted strong antibacterial activity. The SLMed Fe-30Mn- 6Cu (i) exhibited a fully γ-austenite microstructure with fine equiaxed grains (~7 μm) containing Cu-enriched intergranular second-phase particles; (ii) demonstrated a yield strength of ~230 MPa—approximately ~24% higher than that of SLMed Fe- 30Mn—along with improved tribological performance, a reduced hysteresis loop area indicating extremely low saturation magnetization and magnetic susceptibility, and a biodegradation rate three times higher compared to the Cu-free counterpart; and (iii) achieved a bacteriostatic rate exceeding 99% against Escherichia coli and Staphylococcus aureus, alongside excellent cytocompatibility and promotion of osteogenic differentiation in MC3T3-E1 cells. These findings provide insights into the structure-property-function relationship of multifunctional Fe-Mn-Cu alloys and their promising applicability in orthopedic implants.

Keywords

Antibacterial activity / Biodegradation / Fe-Mn-Cu alloys / Magnetic resonance imaging compatibility / Osteogenic differentiation / Tribological performance

Funding

The study was financially supported by the National Natural Science Foundation of China (No. 52305313), the Natural Science Foundation of Hunan Province (No. 2023JJ40553), and the Natural Science Foundation of Shandong Province (No. ZR2023ME181).

Conflict of interest

The authors declare they have no conflict of interest.