On the addition of Au and Pt to a Fe-Mn-Si alloy for biodegradable implants.

Fe-Mn based alloys are particular promising for the development of temporary bioabsorbable implants. They exhibit good performance in biological tests, improved mechanical properties and more adequate degradation rates than pure iron for the targeted application. In addition, this system possesses an excellent processability, making it particular suitable for designing thin structures and tailoring the chemistry by alloying. Accordingly, earlier works indicated that by adding Si to Fe-Mn, mechanical properties and long-term degradation behaviour could be improved. This study builds up on the alloying approach adding a fourth noble element to further enhance degradation rate, strain-hardening performance and to pave the way for preparing functionally optimized implant materials as Pt and Au can increase radiopacity and their ions are potentially antibacterial. The alloys were prepared by arc-melting and processed into sheets. Dissolution behaviour was measured by electro-chemical corrosion and static degradation set-up, mechanical properties were studied in tensile mode. Particular emphasis is placed on the different evolution of microstructure in these alloys after rolling and its impact on passivation and degradation. This study demonstrates that quaternary Fe-Mn-Si-(Pt, Au) alloys can be prepared successfully, further accelerating degradation in comparison with ternary alloys.