Potentiodynamic polarization studies on amorphous Zr46.75Ti8.25Cu7.5Ni10Be27.5, Zr65Cu17.5Ni10Al7.5, Zr67Ni33 and Ti60Ni40 in aqueous HNO3 solutions

Potentiodynamic polarization studies were carried out on virgin specimens of Zr-based bulk amorphous alloys Zr46.75Ti8.25Cu7.5Ni10Be27.5 and Zr65Cu17.5Ni10Al7.5, and conventional-type binary amorphous alloys Zr67Ni33 and Ti60Ni40 in solutions of 0.2 M, 0.5 M and 1.0 M HNO3 at room temperature. The values of the corrosion current density (Icorr) for the bulk amorphous alloy Zr46.75Ti8.25Cu7.5Ni10Be27.5 were found to be comparable with those of Zr65Cu17.5Ni10Al7.5 in 0.2 M and 0.5 M HNO3, but the value of Icorr for the former was almost three times more than that of the latter in 1.0 M HNO3. In the case of conventional binary amorphous alloys, Ti60Ni40 showed lower value of Icorr as compared to Zr67Ni33 in 0.5 M and 1.0 M HNO3 and a comparable value of Icorr in 0.2 M HNO3. In general, the binary Ti60Ni40 displayed the best corrosion resistance among all the alloys in all the cases and the corrosion current density (Icorr) for all the alloys was found to increase with the increasing concentration of nitric acid. It is noticed that the bulk amorphous alloys do not possess superior corrosion resistance as compared to conventional binary amorphous alloys in aqueous HNO3 solutions. The observed differences in their corrosion behavior are attributed to different alloy constituents and composition of the alloys investigated.