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

Abstract

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 mu m, with keeping the average size of TiC powder as 1 mu m. 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. (c) 2005 Elsevier Ltd. All rights reserved.