Enhancing the corrosion resistance of biomedical material molybdenum–rhenium alloys in simulated body fluids via rare earth oxide doping

An investigation into the corrosion behavior of pure Mo50Re and rare earth oxide-doped Mo50Re, produced by spark plasma sintering, was performed in Ringer’s physiologic solution at a temperature of 37 °C. Potentiodynamic polarization testing indicated a reduction in corrosion current density from 3.1 μA·cm^‒2 for the pure Mo50Re to 1.6 μA·cm^‒2 for Y-doped, 1.5 μA·cm^‒2 for La-doped, and 2.1 μA·cm^‒2 for Y-La co-doped variants. Furthermore, electrochemical impedance spectroscopy revealed that the charge transfer resistance for the rare earth-doped alloys was higher, with values reaching up to 2.4 × 10⁴ Ω·cm² for Y-doped, 3.4 × 10⁴ Ω·cm² for La-doped, and 2.9 × 10⁴ Ω·cm² for Y-La co-doped materials, in contrast to the 1.7 × 10³ Ω·cm² resistance observed for the pure Mo50Re. The research highlights the significant enhancement in corrosion resistance conferred by the incorporation of rare earth elements, ascribed to their ability to refine the grain size and purify the grain boundaries.