WC-Co Cemented Carbides with Ultrahigh Fracture Strength

摘要

WC-Co cemented carbides were prepared by sintering the in-situ synthesized composite powdersrnwith a constant Co content and VC or Cr_3C_2 particles of different size scales. With an optimized carbonrnaddition and doping of the microscale VC or nanoscale Cr3C2 particles, the ultrahigh fracture strengthrnwith mean values above 5000 MPa have been obtained in the prepared cemented carbide bulkrnmaterials. By detailed crystallographical analyses of the configuration and interactions of WC, Co, VCrnand Cr_3C_2 phases, the effects of the VC and Cr_3C_2 particle size on the microstructure and mechanicalrnproperties of the cemented carbides were demonstrated. The mechanisms for the reinforcement of thernfracture strength, concerning the binder distribution, characteristics of phase boundaries andrndislocations motion in the WC grains were proposed, and the dominant factors for the ultrahigh fracturernstrength of the cemented carbides were discussed.