Microstructural Changes of Ods Ferritic Steel Powders During Mechanical Alloying

The ODS ferritic steel powder with chemical composition of Fe-14Cr-2W-0.3Ti-0.3Y2O3 was mechanically alloyed (MA) either from elemental or pre-alloyed powders in a planetary ball mill. Different milling parameters have been used to investigate their influence on the morphology and microstructure of the ODS ferritic steel powder. The time of MA was optimized by studying the structural evolution of the powder by means of X-ray diffractometry and TEM. In the case of elemental powder very small, about 10 žm in diameter, spherical particles with a large surface area have been obtained. Flakey-like particles with an average size of about 45 žm were obtained in the case of the pre-alloyed powder. The lattice strain calculated from XRD spectra of the elemental and pre-alloyed powders exhibits a value of about 0.51 % and 0.67, respectively. The pre-alloyed powder after consolidation process showed the highest density and microhardness value.