Effect of plasma ion immersion treatment on the structure and phase state of the TiNi alloy for medical implantants

In this paper we present the results of studying the structure and phase composition of the medical alloy Ti-50.9 at. % Ni processed by method of plasma ion-immersion implantation (PIIID) by Si ions. TEM/EDS/XPS analyses were used. After ion-plasma treatment, a separate amorphous layer is formed on the TiNi sample surface, containing Si. It is found that diffusion transformations in TiNi during PIID occur. The aging in the bulk of samples takes place with the separation of coherent Ti₃Ni₄ precipitation. After cooling in the alloy a B2→R martensitic transformation is realized. (paper)