Multisine impedimetric monitoring with an in-depth distribution of relaxation times analysis of WE43 and AZ31 magnesium alloys corrosion

Abstract

This research aims to develop and utilize an impedance-based tool for monitoring non-stationary electrochemical processes, coupling the multisinusoidal perturbation signal approach and distribution of relaxation times (DRT) analysis for the first time. The approach was used to distinguish independent processes occurring at the surface of AZ31 and WE43 Mg alloys undergoing corrosion in Hank’s Balanced Salt Solution at 37 °C. We highlighted two common processes related to corrosion product layer formation. Detailed DEIS-DRT analysis was capable of real-time identification of a unique third process for the WE43 alloy, resulting from a spatially localized filiform corrosion attack in the vicinity of intermetallic particles. The proposed tool proved to be highly efficient in terms of studying non-stationary processes, while the DRT analysis allowed for an in-depth and precise localization of the number and the kinetics of the ongoing processes. The corrosion mechanism description was supported by numerous microscopic and spectroscopic tools.