Mechanical Properties of Cr3B4 Cermets Cemented by Different Metallic Binders

Cr3B4 cermets cemented by cobalt and iron as a metallic binder up to 20 wt% were prepared by hot pressing at 1500 and 1800℃ under a pressure of 14 and 41 MPa for 1hr. The binder addition enhanced the densification of Cr3B4 cermets due to the formation of liquid metal and its flow into the pores. It is also found that the temperature and pressure have a pronounced effect on densification. The densification of Cr3B4 is enhanced by the addition of cobalt and iron due to the liquid phase formation, therefore, the hardness and fracture toughness were improved, to a certain extent. A composite with a both high Vickers hardness of 35.98 GPa and a modest fracture toughness of 2.5 MPa.m1/2 could be obtained by the addition of 8 wt% cobalt at 1500℃ and 14 MPa. There is an overgrowth of the boride grains which surly reduces the hardness but has less impact on the fracture toughness.