Abstract
Growth of oxide particles during annealing at 1100-1300°C in dispersion strengthened alloy, Fe-25%Cr-28%Ni-3vol.%oxide (a-Al2O3, MgO, Er2O3, TiO2 and ZrO2) prepared by the method of powder metallurgy were investigated. Results obtained are as follow;
(1) Oxide particles are coagulated by annealing at 1100-1300°C in air and in hydrogen stream.Rates of the particle coagulation are smaller in hydrogen stream than in air. Activation energies for the coagulation are larger in hydrogen stream than in air. Volume fraction of the oxide particle increases with heating, and increment of the volume fraction is larger in air than in hydrogen stream. It seemed that these particles change to complex compounds during annealing.
(2) The coagulation of the particle in these alloys come about in a mechanism of the particlemigration along the grain boundary, while the particles react on impure oxides such as Cr2O3 mixed in the preparation of the alloys.
