Influence of a Novel Thermomechanical Processing Route on the Structural, Mechanical, and Corrosion Properties of a Biodegradable Fe-35Mn Alloy

Abstract

Recent studies have focused on developing temporary metallic implants made from biodegradable biomaterials, such as iron and its alloys, along with the associated manufacturing methods. These biomaterials allow the implant to gradually degrade after fulfilling its function, which reduces the risks of complications associated with permanent implants. Iron is particularly appealing from a structural standpoint, and adding manganese enhances its potential for use. The Fe-35Mn alloy demonstrates excellent mechanical properties and degradation characteristics, making it an ideal choice within the Fe-Mn system. As a result, new processing techniques can be applied to this alloy to further improve its performance. The objective of this research is to propose a new processing route and evaluate its impact on the properties of the Fe-35Mn alloy. The experimental alloy was produced using an arc melting furnace, followed by homogenization, hot swaging, and solution treatment. Alloy characterization was conducted using various techniques, including X-ray fluorescence (XRF), optical microscopy (OM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), microhardness testing, tensile strength measurements, Young’s modulus determination, and potentiodynamic polarization analysis. The microstructural evolution throughout the applied processing route was analyzed in relation to the alloy’s mechanical performance and corrosion resistance. The typical microstructure of the Fe-35Mn alloy is primarily composed of austenitic grains stabilized at room temperature. Its mechanical properties—yield strength (297 MPa), ultimate tensile strength (533 MPa), and elongation to failure (39%)—are comparable to, or even surpass, those of conventional biomedical materials such as 316 L stainless steel and pure iron. The reduced Young’s modulus (171 GPa), compared to other alloys, further underscores its potential for biomedical applications. Electrochemical testing revealed lower corrosion resistance than that of similar alloys reported in the literature, with a corrosion potential of −0.76 V and a current density of 3.88 µA·cm−2, suggesting an enhanced corrosion rate.