Wear response of metastable β-type Ti-25Nb-2Mo-4Sn alloy for biomedical applications

The wear response of a newly developed metastable beta-type Ti-25Nb-2Mo-4Sn (abbreviated as Ti-2524) alloy was investigated and compared with that of (alpha+beta)-type Ti-6Al-4V alloy. Experimental results show that solution-treated (ST) Ti-2524 specimen has the lowest wear rate due to the combined effects of excellent ductility and lubricative Nb2O5. Although similar Nb2O5 forms on the surface of the cold rolled plus annealed (CRA) Ti-2524 specimen, the beneficial effect of Nb2O5 on the wear resistance is counteracted by the increase in wear rate caused by low elongation. Thus, the wear rate of the CRA Ti-2524 alloy is higher than that of ST Ti-2524 specimen. As for the ST Ti-6Al-4V alloy, no lubricative Nb2O5 forms on its worn surface owing to the absence of Nb. In addition, the ST Ti-6Al-4V alloy exhibits an elongation roughly similar to the CRA Ti-2524 specimen. Therefore, the ST Ti-6Al-4V specimen possesses a higher wear rate than the CRA Ti-2524 specimen.