Fabrication and stability of ultrafine ZrC nanoparticles dispersion strengthened sub-micrometer grained W alloy

•An ultrafine ZrC nanoparticles dispersion strengthened sub-micrometer grained W-0.5 wt% ZrC alloy (W-ZrC) was fabricated by an improved ball milling and spark plasma sintering (SPS) process.•A quantitative relationship between Vickers micro-hardness and grain size of sintered W-based alloys has been proposed, indicating the potential value for foreboding the Vickers micro-hardness of some newly developed tungsten materials after getting the grain size information especially for the sintered tungsten alloys.•The evolution of microstructure with annealing temperature indicates that the recrystallization temperature of this W-ZrC alloy is up to 1400 °C ∼ 1500 °C, which is higher than that of the hot rolled one (∼1350 °C). An ultrafine ZrC nanoparticles dispersion strengthened sub-micrometer grained W-0.5 wt% ZrC alloy (W-ZrC) were fabricated by an improved ball milling and spark plasma sintering (SPS) process. The as prepared W-ZrC has an average grain size of ∼0.86 μm with an average second-phase particle size of 24 nm. The thermal stability and thermal shock resistance of this W-ZrC alloy were investigated systemically by comparison with the reported rolled specimens. For this W-ZrC alloy, the evolution of microstructure with annealing temperature indicates that the occurrence temperature of grain growth is up to 1400 °C–1500 °C, which is higher than that of the as-rolled one (∼1350 °C). Moreover, the crack threshold (100 shots) at room temperature is in the range of 0.22−0.33 GW/m2, which is similar to that of most carbide dispersion strengthening tungsten alloys. In addition, a quantitative relationship between Vickers micro-hardness and grain size of sintered W-based alloys has been proposed.