Pressureless sintering of WC-TaC binderless carbide

Abstract Binderless carbides (WC-(0–10)wt.%TaC) were prepared via pressureless sintering at a relatively low temperature of 1850 °C using micro-scaled initial powders. The phase evolution, microstructures, physical and mechanical properties, and densification behaviors of these materials were investigated. The results showed that the binderless carbides had a single WC phase regardless of TaC addition. TaC dissolved into WC, resulting in the lattice expansion of the latter. With the increase in TaC addition up to 10 wt%, the lattice parameters, a and c, of hexagonal WC, as calculated using the Nelson–Riley extrapolation method, increased from 0.290963 nm to 0.284075 nm–0.291838 nm and 0.284929 nm, respectively. The proper addition of 2.5 wt% of TaC inhibited the coalescence of the WC particles and resulted in a homogeneous grain size. Furthermore, the dissolution of TaC improved the sinterability and facilitated densification, resulting in a low porosity of A02B02C00. The increase in TaC addition mitigated the mechanical properties owing to the decrease in sinterability, increase in porosity, and abnormal grain growth. Hence, almost full densification of binderless carbide was successfully consolidated at 1850 °C. The Vickers hardness of 26.51 GPa and fracture toughness of 9.95 MPa m1/2 achieved approached the corresponding levels of binderless carbides prepared via pressure-assisted sintering.