An x-ray diffraction investigation of heat-treated WC-Co sintered carbides

This work presents the results of an x-ray diffraction investigation of the microstructure of WC-Co sintered carbides after hardening under different conditions. The materials studied were medium grain alloys with 6.15 and 25 wt. % cobalt. A portion of the specimens was hardened under different conditions differing in temperature and hold time. The heating was done in a salt bath. The specimens were annealed in vacuum at 1373 K for 2 h. Hardening of sintered carbides from 1300 K and more may lead to a change in the phase composition of the alloy under conditions of long holds at the hardening temperature. With an increase in hardening temperature there is an increase in the solubility of tungsten in the binder phase and an increase in stresses in the carbide and cobalt phases. The optimum heat-treatment cycle for sintered carbides corresponds to the maximum solubility of tungsten in cobalt with the minimum change in phase composition and stressed state of the phase. Tables are included