Electrodeposition of Fe–Mn Alloys from Chloride-Based Bath: A Preliminary Study for Biomedical Applications

Fe–Mn alloys are promising candidates for less-invasive and temporary implants such as bioabsorbable stents. However, their composition and microstructure must be tailored to assess an adequate corrosion rate for the desirable lifespan of the stent. This study aimed to evaluate the development of Fe–Mn alloy and its structure and properties correlation when processed by electrodeposition. Planar samples were produced by potentiostatic deposition at two different potentials, −1.3 and −1.7 V vs. Ag/AgCl, from a chloride-based acidic electrolyte with different amounts of NH4Cl. It was verified that, in more negative deposition potentials, the deposition interface changes from planar to dendritic, leading to more ramified deposits with a high level of defects like cracks and pores. More negative potentials also increased the Mn content in the deposit from 0.8 to 5.2 wt.% Mn. The microstructure was composed of a single phase of (Fe, Mn) solid solution in the −1.3 V vs. Ag/AgCl deposit, while the deposit obtained at −1.7 V vs. Ag/AgCl exhibit two phases, one rich in Mn and the other rich in Fe. A higher concentration of NH4Cl in the electrolyte leads to an increase in the Mn content (5.2 wt.% Mn), maintaining the monophasic microstructure. Although several challenges still remain, these results prove that is possible to obtain Fe–Mn bioabsorbable alloys by electrodeposition, which opens a new processing route for these alloys.