X-ray Photoelectron Spectroscopic Analyses on the Corrosion-Resistant W-Cr-Ni Alloys in 12 M HCl

Abstract

The high corrosion behavior of the sputter-deposited amorphous or/and nanocrystalline W-Cr-(4-15)Ni alloys was investigated by corrosion tests, electrochemical measurements and X-ray photoelectron spectroscopy (XPS) including angle-resolved measurements in 12 M HCl at 30℃, open to air. Particular attention was paid to the effects of tungsten, chromium and nickel metals addition on the surface composition of the passive films formed on the ternary alloys which is related to the corrosion-resistant as well as the anodic passivity of the alloys. Corrosion rates of the alloys (～0.85-3.00 x 10^-2 mm/y) are about four and three orders of magnitude lower than pure chromium and nickel, respectively, and even slightly lower than tungsten metal. Surface analyses by XPS including angle-resolved measurements revealed that the high corrosion resistance of the ternary W-Cr-(4-15)Ni alloys is mostly due to the formation of homogeneous passive oxyhydroxide films consisting of all alloying cations of the alloys. The beneficial effect of the simultaneous addition of chromium and tungsten is based mainly on the synergistic interaction between chromium and tungsten cations in the homogeneous oxyhydroxide passive films to improve the corrosion behavior as well as the passivity of the W-Cr-(4-15)Ni alloys in 12 M HCl.