Influence of TaC/(Mo ₂ C+TaC) ratio on the microstructures and mechanical performances of in situ TiB ₂ /Ti(C,N) cermets

Abstract TiB 2 /Ti(C,N) cermets were synthesized using Co‐C‐BN‐Ti‐Mo 2 C‐TaC powders. The influence of the TaC/(Mo 2 C+TaC) mass ratio on the microstructures and performances was studied. Results indicated that Mo from Mo 2 C primarily resided in the binder. As the TaC/(Mo 2 C+TaC) mass ratio was within the range of 0−0.2, excess Mo combined with some Co to form Co 3 Mo. Raising the ratio decreased the amount of metal liquid. This change shortened the diffusion distance of atoms toward Ti(C,N), thereby increasing the relative density of cermets. In contrast, Ta exhibited a faster diffusion rate. Increasing the TaC/(Mo 2 C+TaC) ratio resulted in the formation of core/rim structured (Mo,Ta,Ti)(C,N) and coreless (Ta,Ti)(C,N) solid solution grains. The core/rim structure can prevent the coalescence and growth of Ti(C,N). Nevertheless, an excessive increase in the TaC/(Mo 2 C+TaC) ratio hindered the rapid consumption of C. Consequently, as the mass ratio varied from 0.8 to 1.0, C atoms within the liquid reacted with some Ti to form TiC. At a 0.6‐TaC/(Mo 2 C+TaC) ratio, the cermet displays optimal hardness, K IC , and wear depth, with values of 2145 HV, 9.22 MPa·m 1/2 , and 43.01 µm. This work is beneficial for preparing TiB 2 /Ti(C,N) cermets with a relatively high K IC .