Despite of marked effort to develop non-hazardous corrosion inhibitors for high-strength aluminum, no single compound exhibits all of the favorable properties of the environmentally hazardous chromate. The Cu-rich intermetallics in alloys such as Al 2024-T3 catalyze the reduction of oxygen, the rate-determining step for initiation of localized corrosion. Chromate dramatically slows down oxygen reduction at these sites. Replacements have included a number of inorganic compounds. 
Less systematic research has focused on organic compounds as inhibitors for aluminum alloys since Al has been considered a “hard” acid not susceptible to covalent interaction with organic bases. However, Cu and Zn-containing intermetallics that initiate localized corrosion suggest the use of “soft” thiol organic bases. A rapid assay for the inhibition of oxygen reduction has identified a number of organo-sulfur bases, including low molecular mass thiols, dithiocarbamates, and tiadiazoles. Two compounds, 2,5-dimercapto-1,3,4 thiadiazole (DMCT) and 1-pyrrolidine thiocarboic (1-PYRR) acid salts strongly inhibit oxygen reduction at Cu surfaces. A recent report of electrochemically-stimulated release of DMCT by galvanic reduction of insoluble poly(DMCT) suggests a route to a ‘smart’ galvanically responsive coating.  
Results also show that these compounds inhibit anodic dissolution of Cu, pure aluminum and 2024-T3 aluminum, and exhibit synergy when they are mixed together.