Abstract: The (W, Ni, Fe) composite oxide powder synthesized by spray drying was used as raw materials and reduced at 700 ℃ for 90 min in H₂ atmosphere. The effect of La and Y on H₂-reduction of (W, Ni, Fe) composite oxide powder was studied. Phase composition analysis, crystal size caculation and particle morphology of the reduced powder were measured by X-ray diffraction, TEM and SEM, respectively. The F_sss particle size and special surface area of the reduced powder were also measured. The results show that the phase composition of the composite powder reduced are W and γ-(Ni, Fe) without the rare earth elements, but new phase of La(Ni_0.75W_0.25)O₃ or Y(Ni_0.75W_0.25)O₃ appears in the reduced composite powder with adding La or Y. The particle morphology is spherical without the rare earth elements, but the particle morphology is nearly spherical or polyhedron with adding La or Y, and the effect of rare earth element on particle morphology increases with the increase of rare earth element content. When the rare earth element content is between 0-0.8 %, the d_BET , F_sss and crystal size of the reduced powder decrease greatly with the increase of the rare earth element content, and the dispersity of the composite powder enhances distinctly. When the same content of rare earth elements is added, the order of effect degree on powder properties is that Y>La-Y>La.

Key words: W-Ni-Fe composite oxide powder; hydrogen reduction; La; Y