Nickel-titanium based nanocomposites for orthopedic applications: the effects of reinforcements

Abstract

Owing to better mechanical properties and shape memory effect, the nickel-titanium (NiTi) alloy is a favorable material for orthopedic implants. However, low wear resistance and limited biocompatibility of NiTi can be enhanced by nano-sized reinforcements. Several NiTi-based nanocomposites are developed using nano-sized ceramic reinforcements. Similarly, bioceramic (i.e., HAp) reinforced NiTi nanocomposites are also developed to improve their bioactive properties. However, these nanocomposites show high interconnected pores that severely affect their mechanical strength, corrosion resistance, and biocompatibility. Therefore, some further improvements are required to balance the mechanical and biological properties of NiTi-based nanocomposites. This paper provides a better understanding of NiTi-based nanocomposites developed for orthopedic applications and the resultant effects of nano-sized reinforcements on mechanical, wear, corrosion, biocompatible and bioactive properties. Besides, the synthesis of NiTi nanocomposites using the powder metallurgy process and the effects of process parameters on the nanocomposite properties were also discussed.