Enhancement of Mechanical Properties of Low-Density WC-TiC-Co Cemented Carbides

In this work, the effects of composition, carbide grain size, and WC matrix structure on the mechanical properties of low-density WC-TiC-Co cemented carbides have been studied. It is found that increasing the TiC content promotes WC dissolution into TiC to form a (Ti,W)C solid solution. When the TiC particle size exceeds approximate to 2 mu m, the sintered alloys exhibit a mixed microstructure of (Ti,W)C and core-shell-structured (Ti,W)C@TiC grains. Refining TiC to the ultrafine scale eliminates the core-shell structures and generates a transition layer between WC and (Ti,W)C phases. This transition layer forms coherent and semi-coherent interfaces with the adjacent carbides through lattice distortion and dislocation accommodation, which enhances interfacial bonding and increases intergranular fracture resistance. Furthermore, by incorporating ultrafine WC-Co composite powder to partially replace submicron WC, a bimodal grain microstructure is obtained in the sintered alloy, along with the formation of numerous Co-rich nanoparticles within WC grains. The prepared WC-TiC-Co cemented carbides with optimized TiC content and particle size achieve reduced density and enhanced mechanical properties simultaneously. The present findings provide new insights into strengthening and toughening of low-density cemented carbide materials.