In search of martensite : titanium-tantalum shape-memory alloy

Abstract

There is a broad range of life-saving medical implants and devices that rely on the shape-memory (SME) and superelastic properties of various nickel-based alloys [8]. Unfortunately, there is also serious concern about the toxicity of nickel. Titanium based shape-memory alloys have been noted as potentially non-toxic replacements of the more traditional, nickel-based shape memory alloys. In this thesis I present research concerning the potential of SME-capable titanium-tantalum alloys to replace Ni-based alloys in medical implants. A method for heat treatment of Ti -Ta alloys of varying compositions to induce formation of martensite was developed. Heat-treated alloys were then tested for SME and superelastic behavior by means of hot oil recovery tests and were characterized through optical microscopy. Metallographs of some of the samples were taken throughout the processing and testing procedures in order to directly observe changes in microstructure..