Sintering, microstructure and properties of absorbable Fe–Mn-xCu alloys

Abstract

One issue with Fe-based biodegradable alloys is their relatively slow degradation rate inside the body. In addition, the ferromagnetic nature of Fe intensely limits its application in magnetic resonance imaging (MRI). In this work, the role of copper addition on powder processing, microstructure, and performance of the Fe–35Mn alloy is described. Fe–35Mn based samples containing 0 to 10 wt% Cu were fabricated by ball milling, uniaxial cold pressing, and sintering. The alloys were characterized for their compressive strength, corrosion behavior, and magnetic properties. Results of XRD analysis showed that copper addition promoted ferrite to austenite phase transformation during sintering. Microstructures of the alloys containing up to 3 wt% Cu were composed of a simple solid solution and large pores. However, when Cu content increased to 6 wt%, a free pure Cu phase appeared in the microstructure, resulting in enhanced densification by forming a liquid phase during sintering. Consequently, the compressive yield strength continuously increased with increasing Cu content and reached the maximum value of 203 MPa in the FeMn–10Cu alloy. The corrosion rate also increased with increasing Cu content up to 6 wt%. An average corrosion rate of 0.27 mm/year was found for the FeMn–6Cu alloy, which was more than five times the rate of the base Fe–Mn alloy. The magnetic susceptibility of the alloys decreased with increasing Cu content, indicating a higher MRI compatibility.