Research on preparation process for the in situ nanosized Zr(Y)O2 particles dispersion-strengthened tungsten alloy through synthesizing doped hexagonal (NH4)0.33·WO3
Résumé
Doped hexagonal ammonium tungsten bronze [(NH4)х·WO3, HATB] powder used for elaborating oxide particle dispersion-strengthened
tungsten alloys has received much more attention due to its high activity and special opened-tunneling structures. In this article, the in situ
nanosized Zr(Y)O2 particles uniformly distributed in the tungsten alloy was successfully prepared through synthesizing doped α-HATB powder and spark plasma sintering process. The processing route involves a molecular-level liquid-liquid doping technique that causes a large number of nanosized particles within tungsten grains. The synthesis mechanism of α-HATB and phase evolution were detailedly investigated. Over 75 % of WZr(Y)O2 powders particles are less than 3 μm. The determined Sw values (5.7), coefficient of uniformity Cu (2.3) of the W-0.5% Zr(Y)O2 doped tungsten are 5.7 and 2.3, respectively, both indicating the narrower size distribution. The average size of Zr(Y)O2 particles in prepared W alloy are about 250 nm under SEM observation. Through milling of these powders, the particles in W-0.5%Zr(Y)O2 alloy and 92.5W-4.9Ni-2.1Fe-0.5%ZrO2 can further decrease to less than 100 nm in size, which are 8-10 times smaller than those in the state-of-the-art review.
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