Fabrication of W–Y₂O₃–La₂O₃ composite by chemical process and spark plasma sintering

The fabrication of W composite with homogeneous dispersion of Y₂O₃ and La₂O₃ nanoparticles was attempted with the combination process of ultrasonic spray pyrolysis, polymeric additive solution route and spark plasma sintering processes. The Y₂O₃ dispersed W powders were prepared by ultrasonic spray pyrolysis using ammonium metatungstate hydrate and yttrium nitrate. The composite powders with homogeneously coated La₂O₃ on their surfaces were synthesised by calcination of a precursor solution containing lanthanum nitrate and polyvinyl alcohol. Microstructural analysis revealed that composite powders can be successfully produced by the ultrasonic spray pyrolysis and polymeric additive solution route. The composite powder was consolidated by spark plasma sintering yielding a sound microstructure and high hardness. The fine grain size and increased density in composite were mainly attributed to the dispersion of oxide particles and to the enhanced sinterability by the formation of liquid-like phase. The increased hardness was discussed by the observed microstructural features.