Influence of Milling Time on Morphology and Properties of Precursor Powders for 9Cr Oxide Dispersion Strengthened Steel

In order to clarify the influence of milling time on the atomized precursor powders for 9Cr-ODS (Oxide Dispersion Strengthened) steel, the morphology and microstructure of atomized powders and mechanical alloying (MA) powders with different milling time were investigated by scanning electron microscopy (SEM), laser diffraction particle size analyzer, X-ray diffraction (XRD) and Vickers-hardness tester. The experimental results showed that the atomized powders are spherical in shape with the particle size of similar to 47 mu m and the grain size of similar to 2 mu m. With the increase of MA time, the morphology of MA powders becomes from spherical to lamellar structure, then to equiaxed shape. The mean powder size increases firstly then decreases. The grain size decreases quickly at the initial stage of milling process (0-2 h) then trends to reach a saturation value. The Vickers-hardness increases rapidly at the initial stage of milling, then reaches a saturation value.