Study of microstructure and mechanical properties of a Ti-11Mo-11Nb alloy

Among the commercially available titanium alloys, Ti6Al4V alloy is the most widely used in orthopedic applications. However, its high elastic modulus causes stress-shielding effect, while the vanadium and aluminium that dissociate from the parent material can cause long-term health problems, e.g., Alzheimer disease and neuropathy. As a result, metastable β-type titanium alloys are being developed as alternative materials, because they offer low elastic moduli and good biocompatibility. The microstructure and mechanical properties of a Ti-11Mo-11Nb alloy was studied. Microstructures and phases were analyzed with X-ray diffraction, optical, and scanning electron microscopy. Tensile and microhardness tests were also done. The microstructure of the Ti-11Mo-11Nb alloy is predominantly β phase, although the existence of secondary ω and martensite α″ phases cannot be entirely excluded. The reduced mechanical properties and brittleness in the alloy could be attributed to the coarse columnar β phase. The lower elastic modulus obtained can reduce the stress-shielding effect during application.