THE CORROSION BEHAVIOR OF SPUTTER-DEPOSITED AMORPHOUS CR-NB AND CR-TA ALLOYS IN 12-M HCI SOLUTION

Binary Cr-Nb and Cr-Ta alloys containing 29-63 at% niobium and 26-69 at% tantalum, respectively, with a single phase amorphous structure, were formed by a sputtering method. Corrosion rates of amorphous Cr-Nb alloys were about four orders of magnitude lower than that of chromium metal and about one fifth of that of niobium metal in 12 M HCl solution. Corrosion rates of amorphous Cr-Ta alloys were lower than that of tantalum metal and were not detected even after about 1 week immersion in 12 M HCl solution. The Cr-Nb and Cr-Ta alloys were spontaneously passive in 12 M HCl solution, in spite of the fact that chromium dissolved actively in 12 M HCl solution.