Re-passivation current of amorphous Zr65Al7.5Ni10Cu17.5 alloy in a Hanks' balanced solution

To evaluate the repassivation behavior of amorphous phase with chemical and structural homogeneity, time transient of re-passivation current density was measured on amorphous Zr65Al7.5Ni10Cu17.5 alloy and crystalline pure Zr with a momentary fracture of a ribbon shaped specimen in an artificial body fluid. Current density abruptly increased to a peak, J(peak), and exponentially decreased to the constant value, J(infinity), J(peak) and J(infinity) on the amorphous specimen were smaller than those on the crystalline specimen, indicating that the amorphous phase would show the smaller dissolution rate from bare metal surface and from a re-passive film than the crystalline specimen, respectively. On the other hand, decrease rate of the current density on the amorphous specimen was smaller than that on the crystalline specimen, indicating the regeneration of passive film on the amorphous specimen was delayed probably because the amount of metal ions dissolved at the initial stage, i.e. the source of re-passive film, was smaller on the amorphous specimen. Consequently, the total charge for the re-passivation of the amorphous specimen was smaller than that of the crystalline specimen, supposing that the amount of dissolved metal ions during re-passivation was smaller on the amorphous specimen than the crystalline specimen. (C) 2002 Elsevier Science Ltd. All rights reserved.