Understanding the corrosion and bio-corrosion behaviour of Magnesium composites – a critical review

Realising the potential of Magnesium (Mg), several globally leading ventures have invested in the Mg industry, but their relatively poor corrosion resistance is a never ending saga till date. The corrosion and bio-corrosion behaviour of Mg has gained research attention and still remains a hot topic in the application of automobile, aerospace and biomedical industries. The intrinsic high electrochemical nature of Mg limits their utilization in diverse application. This scenario has prompted the development of Mg composites with an aim to achieve superior corrosion and bio-corrosion resistance. The present review enlightens the influence of grain size (GS), secondary phase, texture, type of matrix and reinforcement on the corrosion and bio-corrosion behaviour of Mg composites. Firstly, the corrosion and bio-corrosion behaviour of Mg composites manufactured by primary and secondary processing routes are elucidated. Secondly, the comprehensive corrosion and bio-corrosion mechanisms of these Mg composites are proposed. Thirdly, the individual role of GS, texture and corrosive medium on corrosion and bio-corrosion behaviour of Mg composites are clarified and revealed. The challenges encountered, unanswered issues in this field are explained in detail and accordingly the scope for future research is framed. The review is presented from basic concrete background to advanced corrosion mechanisms with an aim of creating interest among the readers like students, researchers and industry experts from various research backgrounds. Indeed, the corrosion and bio-corrosion behaviour of Mg composites are critically reviewed for the first time to: (ⅰ) contribute to the body of knowledge, (ⅱ) foster research and development, (ⅲ) make breakthrough, and (ⅳ) create life changing innovations in the field of Mg composite corrosion.