Electrochemical approach to repassivation kinetics of Al alloys: effect of applied load

Abstract

This work provides a broad overview of systematic experimental studies carried out to understand the factors governing the transition to a more occluded corrosion front during repassivation of Al alloys, which is manifested by the appearance of an inflection during polarization into the active region. The pit transition potential Eptp is more adequate in evaluating microstructural changes induced by corrosion. Similarly, reaction orders with respect to [Cl­], derived from relationships of iptp and log [Cl­], correlate with intermediate Al oxychloride species limiting passive film formation and/or complex reaction processes involving hydrogen production/uptake. The extent of corrosion propagation on a narrower front can be evaluated by the steepness of the potential decrease with current after the transition onset, as being proportional to local acidity removal. In order to prove thermodynamic and kinetic concepts, thus gaining insight into environmentally assisted cracking, the effect of applied load is being investigated for 7000 series Al alloys