The process and mechanical properties of Nb–Si–Mo–Ti alloy prepared by spark plasma sintering

In recent years, spark plasma sintering (SPS) has emerged as a widespread method to produce high-quality intermetallic-based materials. This paper prepared the Nb–16Si–10Mo alloy and Nb–16Si–10Mo–10Ti alloy using SPS at 1400 °C, 1450 °C, and 1500 °C at a pressure of 30 MPa and a time of 15 min. The influence of temperature on the microstructure and mechanical properties of the two alloys at room temperature was investigated. The corresponding results showed that the relative density of the two alloys exceeded 99.4 %. Besides, adding Ti decreased the relative density and made the microstructure evolve from Nb_ss + Nb₃Si + Nb₅Si₃ phases to Nb_ss + Nb₅Si₃+Ti_ss phases, and the fracture type varied from brittle fracture to the coexistence of brittle fracture and ductile fracture. As the temperature increased, the flexural strength and the fracture toughness decreased, and the maximum hardness and compressive strength existed at 1450 °C. Furthermore, the appropriate sintering temperature was 1450 °C for a connected mechanical property and microstructure. The flexural strength, fracture toughness, hardness, and compressive strength of Nb–16Si–10Mo alloy and Nb–16Si–10Mo–10Ti alloy sintered at 1450 °C were 462.6 MPa and 565.3 MPa, 6.76 MPa m^1/2 and 8.81 MPa m^1/2, 757.6 HV and 626.5 HV, 2359 MPa and 2143 MPa, respectively.