| Abstract Scope |
Revision surgeries for implantable devices are relatively common, often occurring due to infection or stress shielding of the bone. This problem could be addressed by using biodegradable implants that can degrade as the bone heals. Iron, with its excellent fatigue life, is a promising degradable metal, but it suffers from a slow degradation rate. To enhance degradation kinetics, we propose adding magnesium to iron. Magnesium can form galvanic cells in the iron matrix, expediting the otherwise sluggish degradation of iron. However, processing iron and magnesium presents unique challenges due to their large miscibility gap. Additive manufacturing shows promise in processing immiscible metals, leveraging fast cooling rate, natural mixing effects induced by Marangoni convections and small melt pool dimensions. In vitro studies on Fe-Mg samples demonstrated promising degradation kinetics, with the composite degrading approximately 12% faster than pure iron over the same duration. Importantly, the composite exhibited a more controlled pH change with respect to pure Mg, which could address a persistent issue with magnesium-based implants-specifically the release of hydrogen gas that leads to the formation of gas cavities in the surrounding tissue. |