Corrosion: Critical Challenge in Wider Use of Magnesium Alloys

Abstract

Magnesium alloys, given their high strength-to-weight ratio, are very attractive materials for applications such as aerospace and automotive components. They have also been used as fuel cladding material for nuclear engineering applications. However, magnesium alloys have not found widespread application, particularly in corrosive environments, due to their unacceptably rapid corrosion rates. So, there is a great commercial value in finding measures for durable corrosion resistance of magnesium alloys. It may be intriguing that because of the susceptibility of magnesium to corrosion, and the corrosion products of magnesium being non-toxic, there has been recent and increasing interest in these alloys for manufacturing biodegradable temporary implants (e.g., plates, screws, wires etc.). A success in use of magnesium alloy implants could altogether avoid the need for a second surgery that is required when temporary implants are constructed out of traditional materials, such as titanium alloys.The special issue on 'Corrosion of Magnesium Alloys' was proposed with the background of advanced as well as traditional interest in mechanism and mitigation of corrosion of magnesium alloys described above. Some of the topical issues concerning corrosion magnesium alloys are: their use as temporary bioimplants, role of alloy microstructure in corrosion and effective coatings for corrosion resistance and corrosion modeling. There are articles on each of these topics in this special issue. An overview of the articles is presented below.Magnesium alloys are hugely attractive as construction materials for biodegradable temporary implant devices. But their unacceptably rapid corrosion in human body fluid requires a coating that provides the required corrosion resistance, while also being biocompatible. To this end, the first study included in this special issue investigated the hexagonal boron nitride (hBN)-impregnated silane coating for an advanced magnesium alloy (WZ21) for bioimplant applications [1]. This coating was found to provide a five-fold improvement in the corrosion resistance in human body fluid. This study also includes thorough electrochemical analysis, and provides a mechanistic insight into the improvement in corrosion resistance due to the composite coating.In the second study, alloying elements were added to magnesium to develop secondary precipitates for strengthening [2]. These secondary precipitates are invariably highly cathodic to the magnesium alloy solid solution matrix, and hence, cause severe localised corrosion. The large precipitates were found to be more detrimental. Rapid cooling, such as cryogenic quenching after heat treatment, can suppress the formation of large precipitates. The study showed that the alloy subjected

Experimental Study on Hybrid Magnesium Composites for Human Bone Implants

“…Limited corrosion performance of the magnesium and its alloys are the major bottleneck in widespread usage of the same materials. But it can be enhanced by adding reinforcement to making composites and surface modification technologies [39]. The selected reinforcements n-TiO2 and Al2O3 are having acceptable corrosion performance than the pure magnesium.…”

Solution‐Processed Nanocoating of Ca2Nb3O10 and Polydopamine for Anticorrosion on Magnesium Alloy

“…[5] However, magnesium alloys exhibit poor corrosion resistance in aggressive environments because of the low standard potential (À2.37 V), severely blocking their further applications. [6] Therefore, developing effective anticorrosion technology for magnesium alloys has been an urgent issue recently.…”

Effect of Acrylic Resin on the Protection Performance of Epoxy Coating for Magnesium Alloy

“…Magnesium alloy has broad application prospects in aerospace and other fields because of the advantages of high specific strength, specific stiffness, and strong electromagnetic shielding ability. However, relatively high corrosion susceptibility limits its application range [1][2][3][4]. Some surface treatments have successfully improved the corrosion resistance of magnesium alloys, such as anodizing, microarc oxidation, and plasma electrolytic oxidation [5][6][7].…”