Preparation of powder by electrical discharge erosion and sintering of ultrafine WC-5TiC-10Co alloy with high hardness

In this work, studies were carried out on obtaining a powder by electrical discharge erosion (EDE) of a WC-5TiC-10Co cemented carbide, sintering an ultrafine-grained alloy from the obtained powder, and studying the microstructures and properties of the obtained particles and alloys. We have established that with an increase in the pulse energy from 0.5 J to 10 J, the EDE productivity increases linearly. At the same time, energy consumption decreases and tends towards a constant value (3.4–4.2 kWt*h/kg). It has been established that an undesirable change in the carbon content in the resulting powder from the liquid pyrolysis is proportional to the product of the specific energy consumption and the difference in the mole fractions of carbon and oxygen in the liquid. Excess carbon was removed by heat treatment in the appropriate volume of CO2. It has been established that EDE results in a complete dissolution of tungsten in cubic carbide (Ti,W)C, which is retained in the formed particles. During further heat treatment and sintering, new plate-like ultrafine WC grains grow from a supersaturated (Ti,W)C solution. An increased concentration of tungsten is retained during sintering in ultrafine-grained grains of a supersaturated (Ti,W)C solid solution. By reducing the average diameter of the WC grains from 1.45 μm to 0.42 μm and increasing the carbide content (Ti,W)C, the hardness of the obtained alloys increases from 1410 HV in the original alloy to 1650 HV in the sintered alloy. Fracture toughness increases due to formation of lamellar WC grains from 12.9 mPa*m1/2 to 14.1 MPa*m1/2. •WC completely dissolves in (Ti,W)C in particles formed during spark discharge.•Ultrafine lamellar grains grow from a supersaturated (Ti,W)C solid solution.•WC-TiC-Co alloys with ultrafine lamellar grains have high hardness and toughness.•The change in carbon content is proportional to the specific energy consumption and the liquid composition.