Impact of ruthenium on microstructure and corrosion behavior of β-type Ti-Nb-Ru alloys for biomedical applications

Ruthenium (Ru) was confirmed to be a β-phase stabilizer as a titanium (Ti) alloying element which served to suppress both ω precipitation and elemental segregation; the prominence and degree of elemental segregation between the Nb-rich primary dendrites and the interdendritic areas rapidly decreased with minor Ru addition, yielding a more homogenous microstructure overall. Additionally, even minimal Ru additions significantly altered the corrosion potential (Ecorr), yielding a 0.3 V shift in the noble direction over the Ru-free controls, along with a comparable shift in the potential at which the initial passive region begins to fail (Einc). The present result suggests Ru addition can confer a greater resistance to corrosion in β-Ti alloys.