Effect of powder preparation on degradation behavior and cytotoxicity of sintered porous biodegradable FeMnC alloys for biomedical applications

Biodegradable implants have emerged in biomedical applications, particularly for orthopedic fixations, cardiovascular stents, and tissue engineering scaffolds. Unlike permanent implants, they are designed to degrade and be reabsorbed after implantation in the body, mitigating the need for additional surgeries and reducing associated complications. In particular, Fe-Mn-C alloys constitute a new class of promising metallic materials for medical applications due to their outstanding mechanical properties and their biological performances. This study focuses on improving the degradation rates and cytotoxicity of sintered Fe-Mn-C alloys produced using the powder metallurgy process. To evaluate the impact of different powder preparation methods on material properties, two types of powders were used: (1) MX, prepared by mixing Fe, Mn, and C powders for 1 h; and (2) MM, obtained by mechanically milling the same powders for 10 h. Four mixtures with varying proportions of MX and MM were prepared. Two groups of samples were produced: one entirely from MX (A0), and another containing MM at 25 wt.% (A25), 50 wt.% (A50), and 75 wt.% (A75). All samples exhibited a complex microstructure comprising ferrite, martensite, and residual austenite. Degradation behavior assessment in Hanks’ solution over 14 days showed that adding MM increased the degradation rate, from around 0.04 mmpy for A0 to 0.12 mmpy for A25. Notably, all samples showed similar cell viability, in the range of 83%–89% for 1% extract dilution, and were non-hemolytic, with a hemolysis percentage below 1%.