Effect of Mo2C on the microstructure and properties of (W, Mo)C-10Co cemented carbides

Mo2C doped WC-10Co alloys were prepared via an in -situ synthesis method composed of steps of spray drying, roasting, carbothermal pre-reduction and carbonization-vacuum sintering. The effects of Mo2C content on the microstructure and mechanical properties of cemented carbides were studied in detail. The results showed that WC and Mo2C formed a complete solid solution by the current method. With the increase of Mo2C content from 0 wt% to 0.5 wt%, the effects of solution strengthening and fine grain strengthening were obvious, and the grain size was decreased from 0.72 +/- 0.32 mu m to 0.62 +/- 0.27 mu m, while the hardness was improved from 1316 +/- 20 HV30 to 1549 +/- 14 HV30. However, the (W, Mo)C solid solution would deteriorate the fracture toughness of the alloys. With the further increase of Mo2C content to 9 wt%, the lattice distortion in the solid solution became more serious. Meanwhile, the dissolution of more Mo2C in the liquid Co further weakened the dissolution-precipitation process of the solid solution, thus inhibiting the growth of grains and increasing the hardness of the alloys. In addition, with the increase of Mo2C content, the dominant fracture mode of the alloy changed from transgranular fracture to intergranular fracture.