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 alpha-phase size of Ti6Al4V-0.1 wt% Y2O3 significantly decreases. Meanwhile, Y2O3 is activated as nucleation sites, promoting alpha-phase equiaxed transformation and providing excellent ductility. Compared with Ti6Al4V alloy, the yield strength and tensile strength of Ti6Al4V0.1 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.