Metastable beta titanium alloys with high oxygen content – behavior near the stability limit and resulting mechanical properties
Metastable β titanium alloys are hot candidates for use in hip implant production. They possess favorable properties for this application, such as low Young’s modulus, corrosion resistance and with the right alloying elements, they are purely biocompatible. Only few of these alloys however meet the strength requirements established by the currently and massively used Ti-6Al-4V α+β alloy. One of the approaches is addition of 0.7 wt.% of interstitial oxygen into low-modulus Ti-35Nb-7Zr-6Ta alloy which results in yield strength of 1000 MPa and sufficient ductility of 20%. In this alloy, the β phase stability is greatly enhanced by the oxygen, which in turn increases the Young’s modulus. In our efforts, the oxygen content was preserved and content of the other alloying elements was decreased down to alloy with composition Ti-20Nb-7Zr-0.7O. On this way, the stability limit of the β phase was crossed, but a minimum of Young’s modulus was also found, concurrently with preserved yield strength and ductility, resulting in a very promising material for application in the hip implant production.