Spark plasma sintering of ultrafine WC‐10Ni‐ZrC hardmetals: Effects of adding ZrC nano‐powder

Abstract Novel WC‐Ni hardmetals with divergent adding amounts (0‐9 wt%) of ZrC nano‐powder were fabricated by spark plasma sintering the samples at 1350°C under a pressure of 50 MPa. Through systematic characterizations by X‐ray diffraction (XRD) and scanning electron microscopy (SEM) as well as physical properties measurements, the effects of adding ZrC nano‐powder on the microstructure and mechanical properties of the samples were explored. In the sintered samples with ZrC nano‐powder, ZrO ₂ instead of ZrC could be monitored by XRD in the detection limit. SEM observation revealed that the addition of ZrC nano‐powder could suppress the grain growth of WC to a certain degree. As the adding amount of ZrC nano‐powder increased, the relative density of the specimens initially rose and subsequently declined, attaining a maximum of 98.6% for the specimen with 3 wt% ZrC nano‐powder. With the enhancement of the adding amount of ZrC nano‐powder, the Vickers hardness of the acquired specimens initially increased and then decreased, reaching a maximum of about 1800 HV ₁₀ for the one with 3 wt% ZrC nano‐powder. As the adding amount of ZrC nano‐powder increased, the measured flexural strength gradually decreased from approximately 1500 to 1100 MPa.