Characterization and properties of sintered WC-Co and WC-Ni-Fe hard metal alloys

The aim of this study is to explore two different tungsten carbide binders (Co and Ni-Fe) and then impose various sintering temperature treatments. Experimental results show that the optimal sintering temperatures for WC-Co and WC-Ni-Fe hard metal alloys are 1350 °C and 1400 °C for 1 h, respectively. Meanwhile, the WC-Co and WC-Ni-Fe alloys undergo a well liquid-phase sintering and, thus, exhibit excellent mechanical properties. In addition, the sintered WC-Co and WC-Ni-Fe alloys show that when the relative density reached 99.76% and 99.68%, the hardness was enhanced to HRA 84.4 ± 0.5 and 85.3 ± 0.5, and the TRS increased to 2471.2 ± 1.0 and 2524.5 ± 1.0 MPa, respectively. Moreover, the corrosion test results show that the WC-Ni-Fe alloy sintered at 1400 °C had the lowest corrosion current (Icorr) of 1.11 × 10−5 A cm−2 and the highest polarization resistance (Rp) of 2464.61 Ω cm2 in 0.15 M HCl solution. Simultaneously, the fracture toughness of KIC increased to 15.1 MPa m1/2. Compared with sintered WC-Co alloys, the sintered WC-Ni-Fe hard metal alloys possessed much better corrosion resistance and mechanical properties.