Preparation of Co50Ni50 ultrafines by Co-reduction of solution in presence of polymer

The reduction reaction of aqueous Co2+-hydrazine, which cannot be conducted under the common condition, is carried out by using both of low-temperature heating and stirring. Metallic ultrafines are prepared by this method. In the presence of polyvinyl alcohol (PVA), it is absorbed on the surface of particles of the product and forms a structure of complex particle, which is favorable to the stability of the powder size distribution. Co50Ni50 magnetic alloy ultrafines with fee-cubic system can also be prepared from Co2+-Ni2+ hybrid solution by the same method in the presence of PVA. The effect of PVA amount on the particle size and the stability of Co50Ni50 alloy ultrafines are emphatically discussed.