Ni-FREE Ti-Nb-Sn SHAPE MEMORY ALLOYS

摘要

Shape memory effect has been reported in many alloy systems, but industrial and biological applications are restricted to TiNi alloys. This is because TiNi alloys possess excellent shape memory properties and reliability. However, since toxicity of Ni has been recently pointed out, Ni-free shape memory alloys are required to develop for biological applications. This paper describes the shape memory properties of Ni-free Ti-Nb-Sn alloys containing no toxic elements. It is found that M_s is very sensitive to Nb or Sn content and the shape memory alloys operative at around body temperature can be developed by controlling Nb and Sn contents in the ternary alloys. A maximum recovered strain of 3.5% is obtained in Ti-18at.%Nb-4at.%Sn. Another advantage of Ti-Nb-Sn alloys is to have excellent deformability at ambient temperature in comparison with TiNi alloys.