Electrochemical emission during the straining and destruction of an aluminum–magnesium alloy in an aqueous medium

The spatiotemporal structures of Portevin–Le Chatelier deformation bands at the stage of neck formation and fracture of an aluminum–magnesium alloy deformed in an aqueous medium have been studied using a complex of in situ methods, including the method of high-speed video recording of the surface and the electrochemical emission method. The latter is based on the measurement and analysis of jumps in the electrode potential of a deformed metal under conditions when discontinuous deformation is manifested. It is found that discrete electrochemical emission signals in the frequency range from 10 Hz to 10 kHz contain information on the number of deformation bands, the time of their emergence, their growth stages, their statistical temporal structure, etc. A characteristic series of signals was detected at the prefracture stage, which can be considered the electrochemical precursor of neck formation and specimen destruction. The relationship between the emergence of electrochemical emission signals and the localization of plastic deformation and the destruction of an oxide film on the surface of an aluminum alloy that is in contact with an aqueous medium is discussed.