In Situ Atomic Force Microscopy Observations of the Corrosion Behavior of Aluminum‐Copper Alloys

Atomic force microscopy, a powerful, high‐resolution imaging technique for determining the structure of surfaces in gaseous and liquid environments, was used to examine the reactivity of an electropolished surface of a naturally aged aluminum‐copper‐magnesium alloy (2024‐T3) in aqueous hydrochloric acid (0.01, 0.1, and I M ). When first exposed to acid, the matrix dissolved uniformly. Dissolution then accelerated and pits formed predominately in the vicinity of the second‐phase precipitates. The pits developed into characteristic intergranular damage: i.e. , elongated pits (incipient corrosion cracks) along grain boundaries. Postexperimental ex situ energy dispersive x‐ray analysis and Auger electron spectroscopy were employed to characterize the composition of the various surface features of corroded samples.