Aluminum alloys derive their favorable mechanical properties from heterogeneous microstructures. The heterogeneity of these microstructures leads to localized corrosion. Whilst there has been intense research in localized corrosion in the past, a very important question remains unanswered: "How small is too small for microstructural features to behave as unique electrochemical entities or local corrosion hot-spots?" Our prior work has indicated that precipitates on the order of a few nm in size can indeed serve as unique electrochemical entities. In this work, we investigate the corrosion behavior of a new class of Al alloys based on inhomogeneous solid solutions. Through heat treatment, a spectrum of chemical heterogeneities ranging from about a couple of solute atoms to many tens of atoms (atomic clusters) may be formed without local changes in crystal structure. The mechanical properties of these alloys are strongly affected by the atomic scale clustering of solute atoms - whilst in this work we present some results for the corrosion properties (pitting propensity) of such alloys.
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