The presented work was focused on investigating the influence of the (hafnium and zirconium)/molybdenum ratio on the microstructure and properties of Ti20Ta20Nb20(ZrHf)20−xMox (where: x = 0, 5, 10, 15, 20 at.%) high entropy alloys in an as-cast state. The designed chemical composition was chosen due to possible future biomedical applications. Materials were obtained from elemental powders by vacuum arc melting technique. Phase analysis revealed the presence of dual body-centered cubic phases. X-ray diffraction showed the decrease of lattice parameters of both phases with increasing molybdenum concentration up to 10% of molybdenum and further increase of lattice parameters. The presence of two-phase matrix microstructure and hafnium and zirconium precipitates was proved by scanning and transmission electron microscopy observation. Mechanical property measurements revealed decreased micro- and nanohardness and reduced Young’s modulus up to 10% of Mo content, and further increased up to 20% of molybdenum addition. Additionally, corrosion resistance measurements in Ringers’ solution confirmed the high biomedical ability of studied alloys due to the presence of stable oxide layers.

The presented work aimed to investigate the influence of the hafnium/(zirconium and molybdenum) ratio on the microstructure, microhardness and corrosion resistance of Ti20Ta20Nb20(ZrMo)20−xHfx (where x = 0, 5, 10, 15 and 20 at.%) high entropy alloys in an as-cast state produced from elemental powder and obtained via the vacuum arc melting technique. All studied alloys contained only biocompatible elements and were chosen based on the thermodynamical calculations of phase formation predictions after solidification. Thermodynamical calculations predicted the presence of multi-phase, body-centered cubic phases, which were confirmed using X-ray diffraction and scanning electron microscopy. Segregation of alloying elements was recorded using elemental distribution maps. A decrease in microhardness with an increase in hafnium content in the studied alloys was revealed (512–482 HV1). The electrochemical measurements showed that the studied alloys exhibited a high corrosion resistance in a simulated body fluid environment (breakdown potential 4.60–5.50 V vs. SCE).

In this work, the Ti13Zr13Nb shape memory alloy that was naturally passivated in air has been studied towards long‐term corrosion performance in the physiological saline solution. The electronic impedance spectroscopy method was used to detailed study on the electrolyte|passive layer interfacial properties. The equivalent electrical circuit for the pitting corrosion was applied, and the discussion on the electrolyte|electrode interfacial properties was realized with respect to the physical meaning of the used circuit elements. The study shows that the Ti13Zr13Nb alloy is characterized by high corrosion resistance. ESI measurements revealed the formation of a protective oxide film on the Ti13Zr13Nb surface, during 20 days of exposure in 0.9% NaCl solution at 37°C. In the early days of immersion, there was a slight decrease in corrosion resistance, which in the next 15 days remained unchanged, indicating very good protective properties of the formed oxide film. Performed research indicates that the Ti13Zr13Nb alloy is promising biomaterial to medical applications. Copyright © 2014 John Wiley & Sons, Ltd.

Chitosan biocoatings were successfully deposited on the Ti15Mo alloy surface via cataphoretic deposition from a solution of 1 g dm−3 of chitosan in 4% (aq) citric acid.

In this work, the electrophoretic deposition method has been developed for the fabrication of bioactive alginate coatings on the surface of Ti15Mo implant alloy. Thin ZnO lm was deposited cataphoretically as the interlayer prior to anaphoretic deposition of alginate (Alg) which was performed from aqueous solution containing 1 g dmof NaAlg at room temperature. The deposition voltage and time varied in the range 2050 V and 30120 min, respectively. The microstructure of Alg coatings was studied by scanning electron microscope, and the surface roughness was analysed using atomic force microscopy. Structure was studied by grazing incidence X-ray diraction. Chemical composition and functional group were examined using energy dispersive spectrometry and attenuated total reectance Fourier transform infrared spectroscopy methods, respectively. It was found that controlling the deposition conditions it is possible to obtain amorphous Alg coatings of variable thickness and porosity. Mechanism of electrophoretic deposition of bioactive Alg coatings on the Ti15Mo alloy surface was discussed.