A Review on Friction Stir Processing Over Other Surface Modification Processing Techniques of Magnesium Alloys

An enormous amount of research is conducted on aluminium alloys on friction stir process, despite magnesium alloy reporting severe weight reduction when compared to aluminium alloys; a very slight amount of research was testified by friction stir processing of magnesium alloys. Magnesium is highly reactive and susceptible to corrosion in the presence of an aggressive environment. This highly corrosive nature of magnesium limits its applications. Surface properties like crystal structure, composition, and micro structure influence the corrosion and wear property of the material. Coating and alloying like laser surface modifications are performed to passivate magnesium surface from corrosion. Coating techniques, however were found to be insufficient in corrosion protection due to coating defects like pores, cracks, etc, and adhesion problems caused due to poor surface preparation of the substrate, and also impurities present in coating which provides micro galvanic cells for corrosion. Current study analyses the detailed overview of different types of Surface modification methods such as Physical vapor deposition, Chemical vapor deposition, Chemical conversion coating, Ion implantation coating techniques and also work focuses on few of Alloying or Surface processing methods such as Laser surface modification namely Laser surface melting, Laser surface cladding, Laser Shot Peening, Laser surface alloying and Friction stir processing (FSP). Friction stir processing a novel method derived from friction stir welding is used as surface modification method, which modifies micro structure, composition of surface layer without changing bulk properties, for enhancing corrosion resistance property. FSP enhances the micro structure and homogenizes but it is also eliminating the breaking up of the brittle- network phases and also cast micro structure imperfections. Indeed FSP can produce particle and fiber-reinforced magnesium-based surface composites. FSP empowers the manufacturing of magnesium by adding additives. Comparison of the different methods of coating and surface modification has been compared with FSP