LAUSR

ABSTRACT Commercial pure Ti alloys are favorable for biomedical applications; however, they need to be strengthened by the addition of alloying elements. Herein, Ti-Fe alloys modified with Zr were explored to produce alloys that exhibit high strength and ductility and are biocompatible. Ti-Fe extruded materials with Zr solutes were prepared by combining solid sintering and hot extrusion. X-ray diffraction results revealed that the lattice constant of α-Ti and β-Ti increased proportionally with the Zr content, indicating the Zr solid solution behavior. In situ and ex situ observations of the microstructure formation revealed the element Zr, a weak β-stabilizer, and a decreased phase transformation temperature. However, during the cooling process after hot extrusion, the grain growth stagnated at the same temperature, irrespective of the Zr content, resulting in both α-Ti grain refinement and increased β-phase area fraction. The tensile test results demonstrated that 1010 MPa 0.2% yield strength of the Ti-4Fe-13Zr extruded material increased to 156%, compared with that of the base Ti-4Fe material. Furthermore, Labusch model and the Hall-Petch equation were used to quantitatively evaluate the strengthening mechanism derived from the Zr solid solution and the changes in the grain size.