Abstract
Ti β-alloys based on the Ti-Nb alloy system exhibit growing interest in the biomaterial community. The addition of small amounts of Fe and Cr further increases β-phase stability, improving the properties of Ti-Nb alloy. Production of such alloys by powder metallurgy (PM) starting from elemental powders has the problem of lacking homogeneity due to restricted solid state diffusion. To improve mixing and diffusion of the elements mechanical alloying is used. This paper studies the microstructural characterization and mechanical properties obtained by bending tests of Ti-Nb-(Fe-Cr) alloys obtained by conventional PM with elemental powder mixture and mechanical alloying. The mechanical alloying allows a much more homogeneous composition and particle morphology, characterized by rounded and significantly enlarged powder particles. In the sintered samples two phases appear, namely alpha and beta phase. The α phase appears at the grain boundaries and in lamellae growing from the edge inward, formed mainly by Ti and lower Nb content than nominal. The beta phase is enriched with Nb, Fe and Cr. The addition of the both latter elements increases considerably mechanical properties of Ti-Nb alloys, providing increased ductility.
