First-principle study of Ti₅₀Ni_50-xNb_x shape memory alloys for biomedical applications

¹ Department of Physics, Sefako Makgatho Health Sciences University, P.O Box 94, Ga-Rankua 0204, South Africa.
² Manufacturing Cluster, Advanced Materials Engineering, CSIR, PO Box 395, Pretoria, 0001, South Africa.

Abstract

The excellent shape memory effect and biocompatibility of TiNi alloys have revolutionized the scientific and industrial communities, particularly in biomedical applications. These materials can undergo major or quasi-plastic deformation before returning to their original form when subjected to external stimuli like stress or temperature. However, nickel has been shown to be carcinogenic, it may lead to cytotoxicity which can result in infections, follow-up issues, or implant failure. The aim of this study is to improve the biocompatibility of TiNi by substituting Ni with Nb employing the first principle approach. The structural and elastic properties of the TiNi- Nb alloy were investigated using the CASTEP code embedded in Materials Studio. The findings indicated that Ti₈Ni₄Nb₄'s formation energy had increased. The poisons ratio decreased slightly, reaching a value of 0.32 in line with the G/B findings. Increasing Nb content also lowered the density of states at the Fermi levels. It was found that Ti₈Ni₄Nb₄ was the most suitable substitute for TiNi alloys.