Cm. Liao et Rp. Wei, Galvanic coupling of model alloys to aluminum - a foundation for understanding particle-induced pitting in aluminum alloys, ELECTR ACT, 45(6), 1999, pp. 881-888
Pitting corrosion in aluminum alloys has been shown to be intimately associ
ated with constituent particles in the alloys.:Pitting is attributed to the
galvanic coupling of constituent particles:to the matrix. To better unders
tand the mechanism and kinetics of pitting, two model alloys were used in t
his study, emulating the Cu, Fe, Mn containing constituent particles, to me
asure the open circuit potential and galvanic current density associated wi
th particle-matrix couples. The rate of corrosion reaction at the particle-
matrix :couple was found to be controlled by the limiting cathodic current
density and the particle size. The total corrosion current increased with p
article size and limiting current density. The much higher limiting cathodi
c current density for both of-the model alloy-aluminum couples in an acidif
ied, versus a neutral, solution indicated that galvanic corrosion of the pa
rticle-matrix couple contributed not only to the nucleation but also to the
growth of pits in aluminum alloys. (C) 1999 Elsevier Science Ltd. All righ
ts reserved.