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 envir onments, was used to examine the reactivity of an electropolished surf ace of a naturally aged aluminum-copper-magnesium alloy (2024-T3) in a queous hydrochloric acid (0.01, 0.1, and 1 ill). When first exposed to acid, the matrix dissolved uniformly. Dissolution then accelerated an d pits formed predominately in the vicinity of the second-phase precip itates. The pits developed into characteristic intergranular damage: i .e., elongated pits (incipient corrosion cracks) along grain boundarie s. Postexperimental ex situ energy dispersive x-ray analysis and Auger electron spectroscopy were employed to characterize the composition o f the various surface features of corroded samples.