Enhanced Corrosion Resistance of Harmonic Structured Β-Type Ti-25Nb-25Zr Alloy in Aerated Fusayama-Meyer’s Simulated Saliva Solution

In this study, the microstructure of the β-type Ti-25Nb-25Zr alloy is modified to a bimodal harmonic design, exhibiting fine and coarse grains of ∼3 μm and ∼70 μm, respectively. The high-angle grain boundary density of the harmonic Ti-25Nb-25Zr alloy increases nearly fourfold over its coarse-grained counterpart. Both the harmonic and course-grained Ti-25Nb-25Zr alloys show excellent passivation and corrosion resistance when studied electrochemically in Fusayama-Meyer’s simulated saliva solution. The harmonic structure in the Ti-25Nb-25Zr further improves corrosion resistance, almost six times the coarse-grained counterpart. The improved corrosion resistance is attributed to the excessive high-angle grain boundary, which binds the corrosion product to the substrate, restricting further corrosion.