Strengthening Mechanism of Ti-Zr Sintered Alloys with Sc Addition

In this study, Ti-Zr-Sc sintered alloys with excellent biocompatibility were fabricated from the elemental mixture of pure Ti, ZrH₂ and ScH₂ powders, and their microstructures and mechanical properties were investigated to clarify the strengthening mechanism. In particular, the effect of scandium (Sc) used as the third alloying element on the strengthening behavior by grain refinement, oxygen (O) and Sc solid solution, and Sc₂O₃ particle dispersion was quantitatively evaluated by using the theoretical strengthening models. 0.2% YS of Ti-Zr-Sc alloys decreased with Sc content in the range of 0~1.0 at.% Sc, and increased in the range of 1.0³2.5 at.% Sc. In the former, the added Sc elements reacted with O solutes to form Sc₂O₃ particles and resulted in a significant decrease of O solid solution strengthening effect. On the other hand, when Sc content was over 1.0 at.%, the strengthening effects by both Sc solid solution and Sc₂O₃ dispersion were effective, and cause a remarkable increment of 0.2% YS of Ti-Zr-Sc sintered alloys.