Study on the fabricating process of LaB6 reinforced Ti6Al4V by selective laser melting

Abstract

In this study, LaB6-reinforced Ti6Al4V was successfully fabricated by the selective laser melting (SLM) process. TiB and La2O3 with particle-like shapes formed uniformly after the in-situ reaction of LaB6 and Ti6Al4V. The sizes of the TiB and La2O3 particles were around 1 µm and 200 nm, respectively. Due to a combined strengthening effect of the micrometer-scale and nanoscale reinforcements, the mechanical properties of the LaB6/Ti6Al4V samples were enhanced significantly. However, the effect was highly related to the SLM parameters. As the laser power increased, the TiB changed from particle to needle-like shape and La2O3 tended to aggregate and grow into a larger size. Besides, the martensite α-Ti also became coarser, which was disadvantageous to the mechanical performance. The desired inner structure can be obtained by adjusting the processing parameters of the SLM. The best mechanical performance of the SLM LaB6/Ti6Al4V samples was achieved at the laser power of 260 W and the scanning speed of 500 mm/s. The maximum tensile strength and Vickers hardness were 1337.1 MPa and 477.62 HV, respectively, which outperformed the other counterparts significantly. Thus, the results suggest that the in-situ reaction of LaB6 and Ti6Al4V can improve the mechanical properties of the Ti6Al4V alloys effectively.