Investigating local corrosion processes of magnesium alloys with scanning probe electrochemical techniques: A review

The study of corrosion of magnesium and its alloys has emerged a hot topic in the applications of lightweight structural materials. The inherently high electrochemical activity of bare magnesium surfaces still lacks a convincing mechanism to describe the observed experimental characteristics, and it has prompted the development of various types of protective coatings with the aim of slowing metal dissolution. In recent years, new instruments and techniques have been developed to study with spatial resolution the local corrosion processes that occur in metallic materials in general, and for magnesium and its alloys in particular, both for bare surfaces and coated. Scanning microelectrochemical techniques, such as local electrochemical impedance spectroscopy (LEIS), scanning electrochemical microscopy (SECM), scanning vibrating electrode technique (SVET), scanning ion-selective electrode technique (SIET) and scanning Kelvin probe (SKP) can provide information about the local electrochemical activity of metallic surfaces. In the present work, the applications of these techniques in corrosion studies of magnesium and its alloys are reviewed. Assessment of corrosion mechanisms, barrier properties of conventional coatings and active corrosion behavior of self-healing coatings are examined. Limitations and future developments in this area are discussed.(c) 2022 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ) Peer review under responsibility of Chongqing University

Automated summary

The study of corrosion of magnesium and its alloys has become a hot topic in the applications of lightweight structural materials. Protective coatings have been developed to slow down metal dissolution due to the high electrochemical activity of bare magnesium surfaces. New instruments and techniques have been developed to study the local corrosion processes that occur in magnesium and its alloys, including bare surfaces and coated surfaces. Scanning microelectrochemical techniques provide information about the local electrochemical activity of metallic surfaces. This review examines the applications of these techniques in corrosion studies of magnesium and its alloys, evaluates corrosion mechanisms, barrier properties of coatings, and active corrosion behavior of self-healing coatings, and discusses limitations and future developments in this area.