Effects of surface nanocrystallization on corrosion resistance of β-type titanium alloy

Surface mechanical attrition treatment (SMAT) was performed on biomedical β-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe alloy in physiological environment. The surface nanostructure was characterized by TEM, and the electrochemical behaviors of the samples with nanocrystalline layer and coarse grain were comparatively investigated in 0.9% NaCl and 0.2% NaF solutions, respectively. The results indicate that nanocrystallines with the size of 10-30 nm are formed within the surface layer of 30 μm in depth. The nanocrystallized surface behaves higher impedance, more positive corrosion potential and lower corrosion current density in 0.9% NaCl and 0.2% NaF solutions as compared with the coarse grain surface. The improvement of the corrosion resistance is attributed to the rapid formation of stable and dense passive film on the nanocrystallized surface of TiNbZrFe alloy.