Event Abstract Back to Event Microstructure and biodegradation behaviour of new degradable composite - Fe-Mg2Si for biomedical applications Malgorzata Sikora-Jasinska1, 2, Riccardo Casati1, Ehsan Mostaed1, Carlo Paternoster2, Ranna Tolouei2, Diego Mantovani2 and Maurizio Vedani1 1 Politecnico di Milano, Department of Mechanical Engineering, Italy 2 Laval University, Lab. Biomaterials and Bioengineering, CRC-I, Dept Min-Met-Materials Eng & CHUResearch Center, Canada Introduction: Biodegradable metals used for cardiovascular applications are expected to completely degrade upon fulfilling their mission to support the damaged tissue during healing process without generating any toxic effects[1]. Iron has shown promising potential for cardiovascular devices especially in case of stent application[2]. However, its degradation rate is too slow. One approach to solve the mentioned drawback is the use of Fe metal matrix composites, where the second phase is aimed at tuning the corrosion rate. In this study the effect of Mg2Si content (1, 1.5 and 3 wt %) on the microstructure, mechanical properties and corrosion behavior of Fe-Mg2Si composite was investigated as a novel structure for degradable biomedical applications. In vitro degradation of the materials was reported and a corresponding mechanism of degradation was explored. Materials and Methods: Powder metallurgy was selected as a processing tool aimed to fabricate the composite. Micro-hardness test was performed to characterize the mechanical properties of the new material. Modified Hanks’ solution was used for static immersion tests (ASTM G31-72). Samples were immersed for 2 weeks in a controlled environment. Optical and scanning electron microscopy (SEM), X-ray dispersive spectrometry (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used as characterization techniques. Corrosion rates were calculated with weight loss method. Results and Discussion: The reinforcing particles improved the base material – iron matrix- in terms of mechanical strength, micro-hardness and faster degradation rate as well. Surface morphology after in vitro test was varied depending on the powder preparation method (mixing (M) or mechanical alloying (MA)/milling (MM)) – Fig.1. The degradation layer on the pure Fe (A) was found to be composed mainly of iron and oxygen, with traces of phosphorus, chlorine and calcium. Iron has also shown moderate and uniform degradation. After being immersed in Hank’s solution for 14 days localized corrosion can be observed with brown corrosion products covered the surface of sample B (Fe-3%Mg2Si) whereas for sample C (Fe-1.5%Mg2Si), corrosion products almost cover the whole surfaces, indicating a relatively uniform corrosion mode.The degradation of sample D leads to the formation of a thicker and homogeneous FeCO3 deposit on the surface (Fig. 1d). A cohesive degradation layer is formed on the substrate surface, so that it prevents the contact of the material with the electrolyte. The release of Fe ions into the solution was limited due to the barrier effect of the insoluble degradation layer. Sample D revealed the lowest mass loss compared to samples B and C. Conclusions: The results of the present study indicates that pure Fe and Fe-Mg2Si composites are suitable biomaterials for degradable implants. Fe-Mg2Si showed a higher corrosion rate compared to that of pure iron. The preparation method of the starting powders plays an important role in the degradation/passivation process as well as degradation mechanism. To sum up, iron-based composites are promising candidates for biodegradable coronary stent material with proper mechanical properties and faster degradation rate. The authors would like to thank the MRI-Italy for partially funding this research.