Journal of Materials Science, Vol.45, No.13, 3426-3432, 2010
Beneficial effects of yttrium on mechanical failure and chemical stability of the passive film in 6061 aluminum alloy
Recent studies demonstrated that oxygen-active elements such as yttrium improved the resistance of some alloys to wear and corrosive wear. In this work, the breakdown of passive film and chemical resistance of the passive film in Y-free and Y-containing 6061 aluminum alloy samples were studied. It was demonstrated that critical load that caused failure of the passive film on Y-containing specimens was higher than Y-free samples. Also, penetration depth showed that indentation resistances of Y-containing samples were less than Y-free samples. Polarization behavior of Y-containing samples was improved in contrast of Y-free samples in water and acid environments. Y-containing samples had more power to stabilize the oxide film and make it more inert to electron transfer. Results showed that there was an optimum yttrium addition for improving the properties of Al 6061. Results showed that the best percent of yttrium addition was between 1.5 and 4% and more than this the properties of alloy did not improved.