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Functional nanocrystalline metallic iron powder is produced by the method of electro-discharge in the low oxygen environment of water. In order to obtain superparamagnetic iron oxide Fe 3 O 4, the manufacturing Fe particles were oxidized in the oxygen-rich water to continue oxidation process. Besides, the nanocrystalline Fe particle will be oxidized at temperatures of 200° C , 250° C , 300° C , 350° C , 400° C , 500° C and 600° C for 1 h in air to produce iron oxide α- Fe 2 O 3. The X-ray diffraction, SEM and transmission electron microscope (TEM) were used to analyze the crystal structure and the powder morphologies. The results showed that pure Fe and FeO with a pretty narrow particle size distribution ranges from 1 nm to 10 nm were obtained by the method of electro-discharge. After oxygen-rich oxidation treatment the γ- Fe 2 O 3 and Fe 3 O 4 were obtained at room temperature in 10 days. Thereafter, no more transformation was found in water environment. This result proves that Fe 3 O 4 can be a stable superparamagnetic iron oxide. However, for the Fe particles heat-treated at temperatures of 200 to 600° C , α- Fe 2O3 was formed at temperatures above 300° C for 1 h treating time. Further application studies of this material will be presented in our future research works.

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