Ti-Ni shape memory alloys have been successfully used in healthcare and biomedical devices such as eyeglass frames, orthodontic arch wires, guide wires and self-expanding stents, owing to their outstanding shape memory and superelastic properties. Ti-Ni shape memory alloys have also been considered attractive materials for biomedical implants. However, there have been long-standing concerns regarding the risk of Ni allergy and hypersensitivity for long term use due to the high amount of Ni content in Ti-Ni shape memory alloys. Over the last decade, b-type Ti-base alloys have been...