Electrochemical characterization of intermetallic phases common to aluminum alloys as a function of solution temperature

A practically important scenario in the corrosion of aluminum (Al) alloys is the variation in damage characteristics, i.e. mode, rate and morphology, as function of environmental temperature. In order to address this problem from a mechanistic point of view, this paper presents results for corrosion potentials, pitting potentials and electrochemical characteristics for intermetallic particles commonly present in high strength aluminum alloys, for tests conducted in 0.1M NaCl of varying temperature. Tests were conducted between 0 and 60°C via the use of a micro-capillary electrochemical cell. The intermetallics investigated were Mg₂Si, MgZn₂, Al₇Cu₂Fe, Al₂Cu, Al₂CuMg and Al₃Fe. Analysis of the results reveals that the electrochemical behavior of such compounds is heavily dependent on temperature, with ramifications for localized corrosion (and protection) in Al alloys. Examples of this are shown for AA7075-T651.