Strength enhancement of α + β dual phase Ti-4Fe alloys with rhenium addition at room and high temperatures

• Dual phase Ti-4Fe alloys with various Re contents were fabricated by powder metallurgy and thermomechanical processing. • Rhenium was mostly dissolved in the β phase, leading to an increase in area fraction and grain size of the β phase. • 2.5 wt% Re addition increased UTS of Ti-4Fe by 40 % and 80 % at room temperature and 500 ℃, respectively. • Rhenium exhibited higher effectiveness to improve room and high temperature tensile strength than other alloying elements in literature. Dual phase Ti-Fe alloys have been receiving attention for their favorable mechanical performance at room temperature; however, their strength significantly deteriorates at high temperatures. This study aimed to enhance the room temperature strength of Ti-Fe alloys through rhenium (Re) addition, and to investigate its effect on high temperature strength. By powder metallurgy and thermomechanical processing, Ti-4Fe alloys with various Re content were fabricated. As a result, 0.2 % yield strength increased from 750 MPa (Ti-4Fe) to 1433 MPa (Ti-4Fe-4.0Re), while elongation decreased from 30 % to 7 % at room temperature. This improvement was primarily attributed to an increase in the area fraction of the β phase, followed by Re solid solution strengthening in the β phase and boundary strengthening. At 500 ℃, the 2.5 wt% Re addition improved the ultimate tensile strength of Ti-4Fe from 258 MPa to 514 MPa. These findings demonstrate the superior strengthening effect of Re at both room and high temperatures compared to other alloying elements reported in the literature, offering valuable insights for the development of high-performance Ti alloys.