1997 Volume 83 Issue 12 Pages 797-802
The size change of oxide particles in oxide dispersion strengthened (ODS) ferritic steels was quantitatively evaluated by X-ray diffraction and TEM. Althougth yttria (Y2O3) particles are thermodynamically stable and do not have any solubility limit in 13% Cr steel, after 48h mechanical alloying (MA) by high energy ball mill, peaks of Y2O3 or any other peaks of precipitates were not observed. The size change of oxide particles was detected by small angle X-ray scattering. Oxide particles became smaller with MA time. Small addition of titanium was very effective on refining of solid solutioning of oxide particles. By heating of as-MA powders above 1273K, precipitation of new oxide particles which were identified with yttrium and titanium bi-oxide. Recovery and recrystallization properties of ODS ferritic steels were influenced by Y2O3 and titanium content. Extrusion at low temperature was effective to make the grain with low dislocation density and low aspect ratio.