On the fabrication of ultrafine-grained potassium-doped tungsten: Mechanical milling and spark plasma sintering of K-doped W powder prepared by evaporation-condensation method

Bubble strengthened materials have received lots of attention in recent years, and among them, potassium-doped tungsten (W-K) is extremely desirable for very high-temperature applications such as plasma-facing materials in fusion reactors. However, it is difficult to fabricate ultrafine-grained W-K bulk materials by traditional methods. In this study, a novel preparation method of ultra-fine-grained bubble-strengthened material is presented. Unlike traditional routes, W-K mixed powder was prepared by evaporating and condensing pure K on the surface of nanoscale W powder. Two W-K mixing methods using this evaporation-condensation route were developed. Mechanical milling process combined with regular SPS sintering were carried out on the W-K mixed powder, which successfully manufactured ultrafine-grained (0.9 μm) W-K bulk material with a high density (96.4%). This study can provide important reference for the fabrication of other bubble-strengthened materials.