Corrosion Behavior of Ti-Based Metallic Glasses

Abstract

The corrosion behavior of the Ti 47.5 Cu 42.5 Ni 7.5 Zr 2.5 metallic glass as well as its modified glasses by the addition of 5 at% Co, Nb or Ta was investigated by electrochemical measurements. Potentiodynamic polarization was carried out in 0.14 kmol/m 3 NaCl solution and 0.2 kmol/m 3 phosphate buffer solution with 0.14 kmol/m 3 Cl - ion. All the metallic glasses examined were spontaneously passivated with significantly low passive current density in sodium chloride solution and phosphate buffer solution. The additional elements improve the corrosion resistance and the effect of Nb or Ta is particular. The results of XPS revealed that the passive films were rich in titanium and deficient in copper and nickel. The higher corrosion resistance for the modified glasses is attributed to stable and protective passive films enriched with titanium cation contained certain amount of additional elements. In phosphate buffer solution, the pitting potentials for all glasses are higher than those in NaCl solution possibly due to inhibiting ability of phosphate ion absorbing on the glassy surface.