Effect of a small amount of Zn addition on the electrochemical properties of Al-0.1%Sn alloy

Abstract

Anodic polarization characteristics and corrosion resistance of Al-0.1%Sn alloys containing Zn up to 0.3% were examined in NaCl and AlCl₃ solutions. Remarkably less noble characteristics and abnormally low corrosion resistance of solution treated Al-Sn alloys are greatly improved by an addition of Zn0.2% or more. Localized dissolution morphology of Al-Sn-Zn alloys is controlled mainly by dissolution potential, that is, canal-like and (100) type of crystallographic pits are observed in the solution treated and precipitation treated noble alloys respectively. Zn addition has little effect on the microstructure of Al-Sn alloys both solution treated and precipitation treated. A small amount of Zn addition is effective to improve electrochemical properties of Al-Sn alloys in practical use.