Effect of Small Addition of Tin, Silicon and Iron on the Solute Atom Diffusion in the Al 3 wt% Cu 1 wt% Mg Alloy and Its Photoelectrochemical Protection

The formation of the Guinier–Preston–Bagaryatsky (GPB) zones in the alloy AlCuMg is controlled by the solute atoms diffusion. It occurs by nucleation, a growth phenomenon, described by the JMAK model. It is governed by the diffusion of solute atoms and coarsening process described by the LSW theory. The diffusion coefficient of the solute atoms is determined during the GPB zones coarsening in AlCuMg. Small addition of iron and silicon slows down the diffusion of the solute atoms in the alloy during the precipitation of GPB zones. On the other hand, the corrosion resistance of the alloy is considerably improved by photoelectrochemical process; the cathodic protection is achieved by short-circuiting the working electrode to n-CdS illuminated by visible light; the corrosion current decreases by 65% under visible light.