Controlled wet-chemical synthesis of Y-doped tungsten precursors for microstructure and property regulation in WC-Co cemented carbides

This study elucidates the chemical mechanism for synthesizing Y-doped tungsten-based precursors using a wet chemical method and investigates its impact on WC-Co cemented carbides. It is found that the acidity (H + concentration) critically determines the precursor phase, morphology, and Y doping efficiency. At moderate acidity, amorphous white tungstic acid nanoparticles rich in W–OH bonds are formed, enabling efficient Y doping (0.34 wt%) through coordination. The resulting Y-doped WC-Co sintered body exhibits a refined microstructure: the average WC grain size decreases from 0.468 μm to 0.388 μm, the WC phase increases from 89.47% to 92.45%, and the brittle Co₃W₃C phase decreases from 9.46% to 6.64%. Y₂₈O₇₂Co₀.₁₅-type precipitates, identified at grain boundaries, contribute to grain refinement via Zener pinning and likely help stabilize the phase composition. This work clarifies the complete pathway from precursor design to microstructure optimization in WC-Co alloys.