ABSTRACT
The most used metals in biomedical applications are stainless steel, titanium alloys, magnesium alloys and cobalt–chromium alloys. From recent studies, it was observed that stainless steel can cause toxicity in the body and it is also heavy. Titanium alloys have high ductility, but they have a higher elastic modulus compared to the natural bone of human beings. Cobalt alloys have a high elastic modulus compared to natural bone and also their wear resistance is inadequate. Magnesium alloys have similar mechanical properties to natural tissues but because of the corrosive nature of magnesium, it is not suitable for biomedical applications such as bone injuries, dental issues and coronary vein-related issues. Nowadays, the popularity of magnesium alloys in biomedical applications is increasing as they have excellent mechanical properties and the capacity for precipitation of a bone-like apatite layer on their outer layer. Also after clinical use, magnesium degrades in the human body as it is a biodegradable material, and this makes magnesium alloy most suitable for many biomedical applications; for example, magnesium nanocomposites made from magnesium, zinc, calcium and nano-hydroxyapatite powders by using different fabrication techniques show better properties. Magnesium-based nanocomposites show different morphological, physical and chemical behavior required for biomedical application. It has been found that biodegradable and bioactive materials as reinforcements help in improving corrosion resistance as well as mechanical properties of magnesium alloys. Bioactive reinforcements improve the growth of osteoblast cells and deteriorate reparation time, which is important for implants. In this chapter, different magnesium alloys used for biomedical applications are studied and it was found that Mg–6Zn is the most suitable one for biomedical applications, as it shows 100% cell viability. This chapter gives a comparative study of different techniques used in the fabrication and characterization of magnesium alloys used for orthopedic and tissue engineering applications. The fabrication techniques of nanocomposites such as equal channel angular extrusion, powder metallurgy method, friction stir process and high-frequency induction heat sintering are also discussed in this chapter. After studying different fabrication techniques, it was observed that dual-stage sintering powder metallurgy is mostly preferred to stay away from imperfections. A comparative study of different corrosion testing methods used for magnesium alloy is also discussed.
