Nano-structure of Iron Formed by Mechanical Grinding

Nano-crystalline elemental iron powder was successfully formed by high-energy ball grinding. The x-ray diffraction, transmission electron microscopy and Mossbauer spectroscopy were employed to follow the structure changes in the process of mechanical grinding with milling time. The thermal stability of nano-crystalline iron powder was also studied by differential scanning calorimetry. The results showed that the grain size reduces drastically at the initial stage of the milling and reaches 6nm after 40h milling. The broadening of Mossbauer spectrum is attributed to the large fraction of iron atoms existing at the inter-faces for the powder milled.