Effects of Nb and NbC additives on microstructure and properties of WC-Co-Ni cemented carbides

Cemented carbides (WC-Co-Ni) with the addition of Nb and NbC respectively were prepared by the conventional powder metallurgy method. The microstructure and mechanical properties of the sintered samples were analyzed. The results indicated that the addition of Nb or NbC reduced the grain size of WC and Nb had a greater inhibition effect on WC grain growth than NbC. The transverse fracture strength of the samples first increased and then decreased with the increase of the amount of Nb and NbC, and reached 3120 MPa and 2850 MPa respectively when adding 1.0 wt% Nb and NbC. The hardness of cemented carbides showed an upward trend as the content of additives increased. The fracture toughness decreased with the increases of NbC and Nb contents respectively and the fracture toughness of NbC-added samples was lower than that of Nb-added samples. The impact toughness decreased in a mass with the increase of additives.