Abstract
Structural and metallurgical characteristics of the three types of TiNi shape memory alloys (A-Ti-49.5 at.% Ni, B-Ti-49.2 at.% Ni, C-Ti-41.7 at.% Ni-8 at.% Cu) for medical applications were investigated and compared in presented paper. To achieve information of structural properties of these alloys, the light microscopy, TEM, WDA, EDAX, and X-ray analysis were used. The transformation temperatures of investigated materials were determined by use of the resistometric method. Tensile tests and microhardness measurements were performed. The presence of Ti₂Ni (Ti₄Ni₂(O,N)_x) particles and carbide, nitride, and oxide or carbidenitride inclusions were detected in all the types of alloys. As it follows from the results, the initial structure of individual alloys consisted of B2 and B19' phases but their volume fraction was different at room temperature, depending on the previous treatment. The applied treatment does not influence the determined crystallographical orientation relationships between B2 and B19' phases. As we have found, deformation behaviour of the studied alloys was dependent on the position of the testing temperature with respect to the transformation temperatures as well as on the work hardening intensity.

Key words
TiNi shape memory alloys, structural properties, light microscopy, TEM, WDA, EDAX, and X-ray analysis, crystallographical orientation, B2 and B19' phases, hardening

Full text not available