Abstract
In order to improve the mechanical properties of Ti–29Nb–13Ta–4.6Zr (TNTZ) alloy without increasing Young’s modulus for application in bone prostheses, dispersion strengthening of TNTZ using yttrium oxide (Y2O3) particles was studied. The formation of well-dispersed Y2O3 particles inside grains of Y-added TNTZ is achieved through the reaction of added Y with the oxygen contained in TNTZ. The size and its standard deviation of obtained Y2O3 particles increased at Y concentrations of 0.2 and 0.5 mass%. The addition of Y led to a decrease in the grain size in Y-added TNTZ. Low Young’s modulus was retained in the Y-added TNTZ subjected to cold rolling. The tensile strength and 0.2% proof stress slightly increased in Y-added TNTZ with Y concentrations below 0.1 mass%, whereas they decreased significantly in Y-added TNTZ with Y concentrations of 0.2 and 0.5 mass%. Large Y2O3 particles that formed in Y-added TNTZ with Y concentrations of 0.2 and 0.5 mass% worked as sources for the formation of voids during fracture, which resulted in a decrease in the tensile strength and 0.2% proof stress. Elongation tended to decrease in the Y-added TNTZ as compared to that of TNTZ without any Y addition. As a result, it is found that Y-added TNTZ with improved mechanical properties was obtained at a Y concentration of 0.05 mass% in this experiment. The fatigue strength of Y-added TNTZ was also improved at the Y concentration of 0.05 mass%.
