Martensite structure and mechanical property of Ti-Nb-Ag shape memory alloys for biomedical applications

The martensite structures and the mechanical properties of the solution treated Ti-16Nb-(0, 0.3, 0.7, 1)Ag (at.%) alloys were systematically investigated. For all the Ti-Nb-Ag alloys, different martensite variants are in {111} type I and 211 type II twin relation, while the {111} type I twins are the dominant substructures inside a martensite variant. Substructures of the (011) compound twins are also observed in the Ti-16Nb-1 A g alloy. With increasing the Ag content, the ultimate tensile strength is improved significantly, while the elastic modulus decreases slightly. As a result, the Ti-16Nb-1 A g alloy has a good combination of high strength (840 Mpa) and low elastic modulus.