Combinatorial approach applied to structure and electrochemical properties of titanium-aluminum-iron alloys fabricated by direct metal deposition.

摘要

The titanium based alloys, extensively Ti-6Al-4V, have been used for orthopedic implant materials because of their combination of biocompatibility, corrosion resistance and mechanical properties. However, toxicity of alloying elements, especially vanadium, is a concern.;A new type of titanium based alloy composed of non-toxic alloying elements, such as Al and Fe with suitable modulus of elasticity, strength and corrosion resistance was sought. The optimal ratio of components in the Ti-Al-Fe system was found using a combinatorial approach.;A multicell system for applying the combinatorial technique was made using direct metal deposition (DMD) method, a new manufacturing process for fabricating metal parts directly from Computer Aided Design (CAD) solid models. The DMD process allowed deposition of several layers of different composition on one substrate. Each DMD fabricated sample included several Ti-xAl-yFe alloys. This combinatorial library dramatically reduced the time and cost of the investigation.;The structure, mechanical and electrochemical properties of each new composition were studied using scanning electron microscopy (SEM) with energy-dispersive X-ray analyzer (EDAX ZAF), X-ray diffraction, hardness tests, potentiodynamic polarization, and chronoamperometry. To measure the pitting corrosion characteristics in 49-cell combinatorial library, a cotton tape polarization method was developed. The link between the structure and the properties was developed and described.;As the result of the experimental and theoretical studies two new non-toxic implant materials (Ti-5A1-4Fe and Ti-7A1-4Fe) with high strength and corrosion resistance in physiological media were fabricated. The DMD method was shown to be an effective approach to creating combinatorial libraries for alloy selection.