Effect of Y₂O₃ Dispersion Method on the Microstructure Characteristic of Ni-Base Superalloy.

An optimum route to fabricate the Ni-base superalloys with homogeneous dispersion of oxide nanoparticles is investigated. Two methods for developing a uniform dispersion of oxide nanopar-ticles are compared on the basis of the resulting microstructure. Microstructural analysis reveals that the calcined powder from polymeric additive solution with yttrium nitrate and polyvinyl alcohol represented more fine and uniform distribution of Ni, Y and O elements. The densified specimen by spark plasma sintering at 1000 °C using calcined powder exhibits fine microstructure with oxide nanoparticles compared with that using mechanically alloyed powder, presumably by the particle growth or agglomeration prevention from chelating reaction during the calcination step. The oxide particles in the sintered specimen is identified as Y-Al-O phase, formed by the reaction of Y₂O₃ with Al during calcination and sintering.