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Ti–Ni-based shape memory alloys (SMAs) are among the alloys used as biomaterials. The degree of biocompatibility can be improved by adding different biocompatible elements to these alloy families. In this study, the microstructure, phase transformation temperatures, and biocompatibility of Ti–Ni–Nb–Zr SMAs were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), optical microscopy (OM), differential scanning calorimetry (DSC), and electrochemical potentiodynamic measurements, respectively. The arc melting method was used to manufacture alloys with nominal compositions of Ti–10Zr–(40-x) Ni–xNb (x=0, 2 and 4 at.%). The phase transformation of B19′ ↔ B2 was observed in DSC results, which indicated that the alloys have shape memory behavior. Although martensite plates and dendritic structures are noticeable in OM images, XRD and SEM analyses revealed β-Nb, B19′, B2, and some precipitation phases. The corrosion resistance of the alloys was determined by potentiodynamic corrosion analysis. The alloy with 2 at. % Nb instead of Ni showed the best degree of biocompatibility compared to the other alloys.

The synthesis, characterization, physico-chemical and electrical properties of complexes of pyridine-2-carbaldehyde thiosemicarbazone (PTSC) with transition element cations are reported. The complexes [Fe(PTSC)2Cl2]Cl and [Ni(PTSC)2-(H2O)2]Cl2 were prepared. Molecular structures of these complexes were identified by using elemental analyses, FT-IR, UV-VIS, thermogravimetric and molar conductivity techniques. The structure, along with other physico-chemical studies, established that the complexes of PTSC were low-spin. The spectroscopic study of the compounds showed that the transition metal complexes had octahedral geometry. A spectrophotometric determination of nickel(II) with pyridine-2-carbaldehde thiosemicarbazone in methyl alcohol solution is proposed and the stability constants of the nickel(II) complex were determined by the Job method. The electrical conductivity of the compounds increases with elevated temperature. Their conductivities follows the order Ni>Fe. The calculated values of the activation energy of mobility, Eμ, suggests that conduction in the studied complexes takes place by a hopping mechanism, where one electron hops from one molecule to another.