Y. Matsunaga, T. Yamamoto, Oita University, Oita-shi, Japan; T. Sakuma, Oita University, Oita, Japan; H. Hosoda, Tokyo Institute of Technology, Yokohama, Japan; S. Miyazaki, University of Tsukuba, Tsukuba, Japan
Since Ti-Ni alloys have superior shape memory and superelastic properties, they have been applied as biomedical materials. However, it has been reported that pure Ni is a toxic element and causes Ni-hypersensitivity. Although clear Ni-hypersensitivity to human body in Ti-Ni alloys has not been reported yet, its risk has been pointed out because Ti-Ni alloys contain about 50mol% of Ni. Therefore, it is preferable to develop safe Ni-free Ti-based shape memory alloys. Many b-type Ti-based alloys have been investigated and the appearance of the shape memory effect and the superelasticity has been confirmed in Ti-Nb based alloys and Ti-Mo based alloys. In this work, the superelastic behavior of Ti-Nb-Mo-Al alloys was investigated. The chemical compositions of the alloys were Ti-8Nb-4Mo-3Al, Ti-8Nb-(5-6)Mo-5Al and Ti- (10-12)Nb-4Mo-5Al (mol%).In order to investigate the superelastic behavior, tensile tests were carried out at various temperatures. The superelastic behavior such as Young’s modulus, recovery transformation strain, and critical yield stress are estimated in relation to the Nb and Mo contents and the annealing temperature. The effects of Nb content, Mo content, and annealing temperature on the superelastic characteristics will be discussed.
Summary: The superelastic behavior of Ti-Nb-Mo-Al biomedical alloys was investigated. The chemical compositions of the alloys were Ti-8Nb-4Mo-3Al, Ti-8Nb-(5-6)Mo-5Al and Ti- (10-12)Nb-4Mo-5Al (mol%). In order to investigate the superelastic behavior, tensile tests were carried out at various temperatures. The superelastic behavior such as Young’s modulus, recovery transformation strain, and critical yield stress are estimated in relation to the Nb and Mo contents and the annealing temperature. Main results are summarized as follows. Young’s modulus decreases with increasing Nb and Mo content. The recovery transformation strain increases with increasing Nb content, but it becomes maximum in the vicinity of 5mol% of Mo.
