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Microstructural analysis and Vickers hardness of heat treated biomedical Ti-Cr-Nb alloys

The application of titanium-based alloys in biomedicine has been growing due to their favorable mechanical properties, biocompatibility and excellent corrosion resistance when compared to more conventional stainless steel and Co-Cr alloys. It is known that β-phase of titanium provides a better properties of titanium alloys for biomedical use then its other phases. Niobium is a biocompatible element which improves β-phase forming and it has beneficial effect on mechanical properties. In this work titanium alloys: Ti80Cr10Nb10, Ti70Cr10Nb20, Ti60Cr10Nb30 were obtained by melting and casting in a laboratory arc furnace in protective atmosphere. Phase analysis by X-ray diffraction showed that all alloys were two-phases (α+β). Heat treatment was performed to obtain β-single phase alloys with assuming of better properties when compared with α+β alloys. Heat treatment was performed at 950C for 3 hours followed by water quenching. Temperature of heat treatment was determined by differential scanning calorimetry. Microstructure of experimental alloys was analyzed by light and scanning electron microscope with energy-dispersive spectrometer. Microscopic observations and quantitative analysis clearly showed that phase transformations occurred. In alloys with lower niobium content α-phase was almost fully transformed to β-phase, but in alloy with higher niobium content martensitic α’’-phase was formed. This needle-like phase may be benefit on shape memory effect of alloy. Vickers hardness values of heat treated alloys were lower than those for as cast alloys and are more acceptable for biomedical application.

Microstructure ; Vickers hardness ; heat treatment ; biomedical alloys ; Ti-Cr-Nb alloys

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