STABILITY OF THE PASSIVE STATE OF AL-W SPUTTER-DEPOSITED AMORPHOUS-ALLOYS

The anodic behaviour of sputter-deposited Al-W amorphous alloys contai ning 15-46 at.% of W Was investigated in borate buffercontaining 0-1 M NaCl by using electrochemical, microscopic and surface analytical met hods. The alloys exhibited a stable passivity within a large potential region, the length of which was dependent on W content in the alloy a nd Cl- concentration in the electrolyte. The alloys underwent pitting at and above an anodic potential which was about 1.5 V higher than the corresponding pitting potential for Al metal. The results were compar ed with those obtained for Al-Mo glasses. A tentative mechanism of a s uperior stability of the passive state of Al-W glasses is discussed.