Microscopic structure and properties of ultrafine cemented carbide with cobalt-iron-nickel composite binder

As the most widely used binder for cemented carbide, cobalt has some problems, such as resource scarcity, high cost, and WC-Co cemented carbide poor corrosion resistance. Considering the production costs and performance improvement, iron and nickel, instead of cobalt, were used to form a composite binder, with which ultrafine cemented carbide was prepared, and the relationships between its microscopic structure and mechanics as well as corrosion resistance and wear resistance were studied. The results show that the increase in Fe/Ni mass fraction ratio in the binder makes alloy WC grains refined and the distribution of binder uneven, and thus the hardness and anti-bending strength of alloys are increased and decreased, respectively. The corrosion resistance of alloys in neutral NaCl solutions was evaluated by polarization curve tests and immersion experiments. The addition of Ni to the binder improves the alloy corrosion resistance, which is attributed to the passivation characteristics of Ni and the formation of films promoting corrosion product. The friction coefficient and wear rate of cemented carbide are negatively correlated with Fe/Ni mass ratio. The improvement in alloy wear resistance is mainly due to the strength enhancement of binder phase and the hardness improvement of alloy caused by WC grain refinement.