Effects of Cr2(C,N) addition on microstructure and comprehensive mechanical properties of ultrafine cemented carbide

Abstract

Fast development of the precision machining industry poses a strong challenge for cemented carbides such as WC-Co, which need to be not only high strength and high hardness, but also able to maintain high toughness. However, following with much enhanced strength and hardness, ultrafine cemented carbides are always suffering from significantly weakened fracture toughness. The present work reports a unique strategy by introducing a nitrogen-contained Cr2(C,N) inhibitor into WC-Co cemented carbides for employing a high strength but without scarifying toughness. We found that Cr2(C,N) can simultaneously refine the WC grain size and stabilize the face-centered cubic phase in Co binders (fcc-Co), leading to a low WC/Co interfacial misfit. Thus, the resultant ultrafine WC-10Co exhibits good comprehensive mechanical properties with a transverse rupture strength of 4910 MPa, hardness of 1721 kg/mm2 and fracture toughness of 10.85 MPa⋅m1/2. The effect of Cr2(C,N) on the microstructures and mechanical properties was investigated in detail to explain the mechanism of Cr2(C,N) toughening of WC-10Co cemented carbide. Our investigation indicates great potential for the utilization of nitrogen-containing inhibitors in the manufacture of high-performance cemented carbides.