Elaboration of Titanium-Nickel Alloy with Special Properties through Mechanical Milling

Abstract

Shape memory Titanium-Nickel alloys, also known as Nitinol, are amongst the most utilized materials with special properties in the medical field. Together with the properties of shape memory and superelasticity, these alloys have a very good biocompatibility. In this study, the equiatomic Ti-Ni alloy was obtained in the form of alloyed powder, starting from elemental high purity powders, through mechanical alloying. Specimens for testing the mechanical characteristics of the material, as well as smaller samples for biocompatibility tests were manufactured. The latter ones were prepared for implantation on live tissue, on Wistar rats and Guinea pigs. The structure of samples was studied by microscopy and X-Ray diffraction analysis. All the results have demonstrated the presence of the TiNi intermetallic compound as the quantitative dominant phase. After applying an adequate thermo-mechanical treatment, the tested samples displayed measurable shape memory effect and superelasticity. The in vivo biocompatibility tests, done according to international standards, demonstrated the material’s bio-inertness in relation with living tissue. The obtained results have shown the possibility to elaborate Ti-Ni biocompatible alloys by mechanical milling and sintering.