Microstructure and mechanical properties of Y₂O₃ reinforced Ti6Al4V composites fabricated by spark plasma sintering

The paper presents the fabrication of (0.6–3.0 wt%) Y₂O₃-Ti6Al4V composites by spark plasma sintering (SPS) with the sintering heating rate of 100 °C/min and the sintering temperature of 900 °C. Ti6Al4V powders and Y₂O₃ powders were admixed by rocking mill for 8 h at 30 Hz. Scanning electron microscopy (SEM) equipped with complete energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) were used to characterize the as-received Ti6Al4V powders, Y₂O₃ powders, the admixed composite powders and the sintered samples. The microhardness, the compressive yield strength and the ultimate strength of as-sintered samples at room temperature were enhanced up to 464.1HV, 1346 MPa and 1583 MPa respectively with a plastic strain of 19.1%, when 2.0 wt% Y₂O₃ was introduced. The mechanical behaviors of 2.0 wt% Y₂O₃-Ti6Al4V composite at 450 °C were also carried out with the yield strength of 832 MPa and the ultimate strength of 1088 MPa. Compared with the sintered Ti6Al4V, the 2.0 wt% Y₂O₃-Ti6Al4V composite has higher yield strength and ultimate strength at elevated temperature with the increment of 54% and 37%, respectively. The mode of fracture was transformed from ductile fracture to a combination of ductile and brittle fractures with the increase of Y₂O₃ content.