Effect of WC/TiC grain size ratio on microstructure and mechanical properties of WC–TiC–Co cemented carbides

Microstructure and mechanical properties of WC–TiC–10 wt%Co cemented carbides fabricated by sintering with hot isostatic pressing (Sinter-HIP) process were investigated. The WC/TiC grain size ratio of WC–TiC–10 wt%Co cemented carbides was controlled by changing the average size of WC powders ranged from 0.5 to 4 μm, with keeping the average size of TiC powder as 1 μm. The microstructures of sintered WC–TiC–10 wt%Co cemented carbides were sensitively dependent on the WC/TiC grain size ratio. In WC–TiC–10 wt%Co cemented carbides with WC/TiC grain size ratio of 0.5, the TiC/(Ti, W)C core-rim phases were distributed in WC/Co matrix. While, in WC–TiC–10 wt%Co cemented carbides with WC/TiC grain size ratio above 0.8, the WC and TiC/(Ti, W)C core-rim phases were surrounded by Co binder phase. Hardness of WC–TiC–10 wt%Co cemented carbide increased with decreasing the WC/TiC grain size ratio from 4 to 0.8 following the modified Hall–Petch type equation. However, the hardness of WC–TiC–10 wt%Co cemented carbides with WC/TiC grain size ratio of 0.5 shows much higher values than that expected by modified Hall–Petch type equation. Transverse rupture strength of WC–20TiC–10 wt%Co cemented carbides increases with decreasing the WC/TiC grain size ratio.