Design and fabrication of a Nb/NiTi superelastic composite with high critical stress for inducing martensitic transformation and large recoverable strain for biomedical applications

A novel Nb/NiTi superelastic composite with a shell-core structure was designed and fabricated to achieve a combination of biocompatibility and superelasticity (large recoverable strain ε accompanied by high critical stress for inducing martensitic transformation σ_SIM). The good biocompatibility is mainly attributed to the outer non-cytotoxic Nb shell that prevents inner NiTi core from direct contact with cells. Meanwhile, the inner NiTi core endows the composite with superelasticity through a fully reversible stress-induced martensitic transformation between B2 parent phase and B19′ martensite. These results might shed some light on design and development of novel superelastic composites for biomedical applications.