Effect of Y₂O₃ addition on microstructure and properties of Ti6Al4V by laser melting deposition

Y₂O₃ particles act as nucleation sites in the additive manufacturing (AM) process of titanium alloy, making its microstructure refined and homogeneous, which is very beneficial for improving properties. However, obtaining good properties requires a good grasp of the amount of Y₂O₃ addition. Excessive addition of Y₂O₃ particles can lead to stress concentration at the tips, increasing the probability of material fracture, so the amount of Y₂O₃ addition must be strictly controlled. We have attempted to add different contents of Y₂O₃ particles during the laser melting deposition (LMD) of Ti6Al4V. The microstructure and properties of Ti6Al4V-xY₂O₃ (x = 0,0.1,0.5,0.9) alloys were studied. The results show that the α-phase size of Ti6Al4V-0.1 wt% Y₂O₃ significantly decreases. Meanwhile, Y₂O₃ is activated as nucleation sites, promoting α-phase equiaxed transformation and providing excellent ductility. Compared with Ti6Al4V alloy, the yield strength and tensile strength of Ti6Al4V-0.1 wt% Y₂O₃ alloy are increased by 7.75% and 10.27%, respectively. What's more, the corresponding elongation increased from 5.97% to 11.53%. In addition, Y₂O₃ has a positive effect on improving the material's tribological properties. The friction and wear test shows that the wear resistance of Ti6Al4V-0.5 wt% Y₂O₃ alloy is improved by 3.6 times. This work provides a new method and abundant data for improving the mechanical properties of Ti6Al4V alloy in AM.