Using ion implantation to study localized corrosion of Al

Abstract A mechanistic-based understanding of corrosion is needed in order to predict aging characteristics and reliability of either electronic or structural components. Although it is well known that the presence of a halide such as Cl − is necessary for pit initiation, the precise role the Cl − plays in the oxide breakdown is not understood. Cl and Ar ion implantation were used to modify air passivated Al using the implantation profile to provide a variation in Cl concentration with depth, in conjunction with varying implant fluences. After irradiation, samples were exposed to a corrosive environment and the electrochemical behavior was characterized as a function of impurity level. The pitting potential varied in an inverse relationship with the Cl concentration when measured in Cl-containing solutions. In solutions without Cl it was estimated that a concentration on the order of 0.5 at.% was required to initiate pitting. Implanting the inert ion of Ar did not enhance pitting.