Fe-Mn-C-Si alloy as possible material for degradable pin implants: surface and in vitro characterization

MELINA HANKOVITS; JOSEFINA BALLARRE; SILVIA CERÉ

Mar del Plata

Congreso; 34th ISE Topical Meeting; 2023

INTEMA

Biodegradable metals are studied as temporary implants in the orthopedic field. They can be used as fixation devices to restore bone fractures due to their adequate mechanical properties, non-toxic degradation products, and the possibility of avoiding a second surgical intervention to remove the device [1]. On this background, Fe-based materials are promising materials due to their degradability and mechanical properties.To overcome the slow degradation rate of pure Fe, the addition of manganese (Mn) to get a FeMn solid solution is under study. By alloying iron with manganese the corrosion rate is increased by the generation of micro galvanic corrosion sites and the magnetic susceptibility is reduced. In FeMn alloys the addition of Si also implies an increase in the γ-austenite phase, which generates a microstructural homogeneity [2]. Also the addition of Si as alloying element presented a promising response in vitro and in vivo in the collagen synthesis and osteogenesis. The aim of this work is to analyze the in vitro behavior of a new FeMnCSi alloy (Fe 26.5Mn 0.5C 1.14Si 0.03P 0.01S), and compare it with the performance of pure iron in simulated body fluid (SBF). The alloy was characterized in terms of electrochemistry response, microstructure and composition by X-ray diffraction and Raman spectroscopy. Assays were performed and analyzed after 2 h, 1 day and 14 days of immersion in SBF.Figure 1 shows the potentiodynamic polarization curves (a) and the Bode diagrams (b) for the FeMnCSi alloy and the comparison with pure Fe after 2 h immersion in SBF. It is observed that pure Fe presents a more positive corrosion potential than the iron alloy, and slight higher corrosion current density. Also from Bode diagrams can be inferred a higher total impedance for the Fe samples compared with the alloy. The degradation of the alloy after 1 day of immersion is enhanced compared with pure iron samples, but after 14 days of immersion it is decelerated. XRD spectrum reveals the presence of crystalline phases related with austenitic phase and Fe-compounds.