Bioresorbable Fe-Mn-C-based cast alloys with enhanced mechanical and corrosion properties for implant applications
In recent years, the interest in bioresorbable materials for clinical treatment of a variety of soft and hard tissue injuries and diseases rises. Such materials shall progressively degrade after fulfilling temporary mechanical support during tissue healing process, so that revision surgeries or long-term side effects are avoided. Besides magnesium- and zinc-based systems, iron-based alloys are potential candidates for that application due to their combination of suitable mechanical properties and excellent processability.
One major challenge of iron-based alloys is the lower corrosion rate compared to other biodegradable metallic systems based on magnesium or zinc. However, the degradation rate can be tailored e.g. by alloying with manganese, silicon or sulfur. Moreover, by alloying with carbon, the strength and cell compatibility can be further improved in comparison to many Fe-Mn-based alloys. Especially Fe-Mn-C systems provide a wide range of superior properties such as excellent processability, high mechanical integrity during corrosion and enhanced corrosion rates in simulated body fluids compared to e.g. Fe-30Mn [1-2].
In this study, the influence of microalloying with sulfur on the microstructure, the tensile behavior and the degradation properties of a cast Fe-30Mn-1C alloy is presented [1-3]. This FeMnCS alloy was prepared by a special casting process implying relatively high cooling rates and pure preparation conditions. Thereby a fine dendritic microstructure composed of austenite and finely dispersed MnS precipitates can be realized. The formation of MnS precipitates was verified by scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM-EDX) and electron backscatter diffraction (EBSD). In vitro studies confirmed cytocompatibility of the examined Fe Mn C (S) alloys . Based on these investigations, a novel degradable Fe-Mn-C-based alloy with enhanced antimicrobial properties is presented.