The microstructure and mechanical properties of Cr3C2-reinforced WC-Cu-10Ni-5Mn-3Sn cemented carbides fabricated via pressureless melt infiltration

The effect of small contents of Cr3C2 dopant (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 wt%) on the microstructure evolution and mechanical properties of WC-Cu-10Ni-5Mn-3Sn alloy is investigated via pressureless melt infiltration tests at the temperature of 1200 degrees C and the infiltration time of 90 min. The results show that with the addition of Cr3C2, there is a change in the amounts of Cr, W and C in the solid solution, whereas the Ni2W4C and Cr7C3 phases appear successively in the binder alloy. Moreover, Cr7C3 readily absorbs W produced by the decomposition of WC, promoting the formation of (W,Cr)Cx and (Cr,W)C phases. The appearance or disappearance of new phases leads to the WC grain size variation, which affects the mechanical properties of the alloy. The hardness and transverse rupture strength first increase and then decrease with the increase of Cr3C2 doping, reaching the maximum values (93.1 HRA and 1720 MPa, respectively) at the Cr3C2 contents of 0.4 wt% and 0.6 wt%, respectively. The impact toughness decreases with the increase in Cr3C2 addition, achieving the most optimal value of 4.65 J/cm2 in the alloy without Cr3C2 addition.