Effect of different sintering process on mechanical properties and microstructure of TiB2-TiN-based cermet material

TiB₂-TiN-NiTi cermet material was prepared by spark plasma sintering technology (SPS). The effects of the sintering process on their relative density, mechanical properties, and microstructure were studied with 74TiB₂-20TiN-6NiTi as the composition system. The results showed that TiB₂-TiN-based cermet material with the best mechanical properties was prepared under the sintering temperature of 1650°C and the holding time of 5 min. The relative density, flexural strength, fracture toughness, and hardness are 97.7%, 762.7 MPa, 5.5 MPa·m^1/2, and 18.47 GPa, respectively. However, if the holding time keeps for 3 min under the sintering temperature of 900°C and then 5 min under the sintering temperature of 1650°C, the relative density, flexural strength, fracture toughness, and hardness of TiB₂-TiN-based cermet reach 99.1%, 931.3 MPa, 5.8 MPa·m^1/2, and 19.15 GPa, respectively. In comparison, they have been greatly improved by 1.4%, 22.1%, 5.5%, and 3.7%, respectively. The final holding time can also affect the mechanical properties of TiB₂-TiN-based cermet material. When it is higher than 5 min, it will cause irregular growth and abnormal growth of grains, which can decrease the flexural strength of TiB₂-TiN-based cermet material.