Effect of YbB6 on Microstructure and Mechanical Properties of Ti-6Al-4V Titanium Alloy

The Ti-6Al-4V titanium alloy with YbB6 addition was fabricated by spark plasma sintering (SPS), and the effects of YbB6 addition on microstructure and mechanical properties of Ti-6Al-4V titanium alloy were investigated. The results show that with increasing the YbB6 content, the microstructure of the composites is clearly changed, and the grains are obviously refined. The in-situ formation of TiB whiskers and Yb2O3 particles is beneficial to the improvement of mechanical properties of the composites. Furthermore, with the addition of 0.6wt% YbB6, the relative density, microhardness, yield strength, ultimate tensile strength, and elongation of the sintered alloys are 99.43%, 4030 MPa, 903 MPa, 1148 MPa, and 3.3%, respectively. Compared to those of Ti-6Al4V alloy, the aforementioned properties of the sintered alloys with 0.6wt% YbB6 are increased by 0.37%, 13.8%, 38.07%, and 17.14%, respectively. The strengthening mechanism is mainly attributed to the microstructure transformation, grain refinement, and dispersion strengthening. With increasing the YbB6 content, the fracture mode is the combination of ductile fracture and brittle fracture.