THE EFFECT OF HEAT-TREATMENT ON THE PITTING BEHAVIOR OF SICW AA2124

The formation of large intermetallics near SiC and potential microsegregation of Mg to this region (resulting in a depletion of Mg in solid solution in adjacent grains) makes the areas adjacent to SiC whiskers more reactive. Because of this increase in reactivity, localized attack near the reinforcement should predominate. The high reactivity of the interface makes it likely that intermetallics will form in the vicinity of SiC whiskers during aging at elevated temperatures and lead to preferential corrosion at the interface. Although preliminary evidence suggests that pits nucleate near SiC whiskers because of the presence of Cu intermetallics, the severity of attack is no worse than observed for the unreinforced alloy.