Surface composition and anodic polarization behavior of zirconium-based amorphous alloys in a phosphate-buffered saline solution

5 atom % of zirconium in amorphous Zr65Al7.5Cu27.5 alloy was replaced with various M (Pd, Ni, In, Mn, Cr, Ti, Nb, and Zr), to evaluate the effects of alloying elements, M, on the surface composition and anodic polarization behavior of the alloy. The surface oxide of the Zr-M-Al-Cu alloys generated in a deaerated phosphate-buffered saline solution, PBS(-), was characterized using X-ray photoelectron spectroscopy. Also, the alloy was anodically polarized in deaerated PBS(-) to determine open-circuit potential, E-open, polarization resistance, R-p, and pitting potential, E-pit. M was incorporated into the surface oxide film with the increase in the oxygen affinity of M, and the relative concentration of Zr to Al, [Zr]/ [Zr + Al], was varied. The R-p at E-open increased and E-pit decreased with the increase in [Zr]/[Zr + Al]. Therefore, the high value of R-p with the large ratio of [Zr]/[Zr + Al] seems to be caused by the high resistance of Zr-containing oxide to general corrosion and/or the preferential dissolution of Al. Zr-containing oxide is susceptible to pitting corrosion. Eventually, the R-p values of Pd-, Ni-, and Nb-containing alloys were high. The E pit values of Pd-, and In-, Zr-containing alloys were high. (C) 2002 The Electrochemical Society.