Effect of annealing temperature on microstructure and mechanical property of Ti-0.3Mo-0.8Ni-0.01Y alloy

In this study, a novel near-α titanium alloy, Ti-0.3Mo-0.8Ni-0.01Y (TA10-0.01Y wt.%), was fabricated using a vacuum non-consumable arc-melting furnace. The effects of annealing temperature (670 °C, 770 °C, and 870 °C) on the microstructure and mechanical properties of TA10-0.01Y plates were systematically investigated. The results showed that the addition of trace Y increased the resistance to dislocation motion. After annealing at 670 °C and 770 °C, the microstructure transformed into equiaxed grains, whereas annealing at 870 °C produced a Widmanstätten structure. The tensile strength decreased from 510.2 MPa to 495.3 MPa and subsequently rose to 572.6 MPa, while the elongation increased from 25.3% to 35.1% and then dropped sharply to 7.6%. EBSD analysis revealed that the average grain size increased from 2.7 μm to 9.63 μm as the annealing temperature increased, accompanied by enhanced recrystallization driving force, eventually leading to complete recrystallization. Dispersed Y 2 O 3 particles suppressed grain-boundary migration and further impeded dislocation motion. This study provides important guidance for optimizing annealing temperature to develop high-performance near-α titanium alloys.