A novel device for mechanical milling, incorporating high voltage, low current electrical discharges was constructed and its application for materials processing investigated [1]. In this paper we present recently obtained results on nanostructural phase formation using this method. Milling experiments were performed under different discharge conditions and resulted in completely different reaction paths for the same reacting species. The effects of spark discharge milling condition on formation of nanocrystals were studied in a large number of different materials. It was found that nanocrystallisation of metallic glass ribbons occurs over very short milling times and is accompanied by the formation of fine particles with narrow particle size distributions. The effect of spark milling on phase transformations was also studied. Strong effects of the introduction of spark discharge conditions on nucleation and interface-controlled transformations were observed.
Results of investigations involving the spark discharge milling of carbon and boron under various atmospheres will be presented. Samples, including activated carbon, toluene and crystalline boron were prepared by both conventional milling techniques and electrical discharge assisted milling. X-ray diffraction revealed a range of nano-fragments present in the milled products, in addition to conventional amorphous and crystalline phases. Results of preliminary transmission electron microscopy characterisation of these fragments will be presented.

[1] A. Calka and D. Wexler, Mechanical milling assisted by electrical discharge', Nature, 419 (6903): 147-151 SEP 12 2002.

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1. Synthesis of nanoparticles using electrical discharges.
2. The effects of oxidized and non-oxidized boron on the Mg-B-H nanohydrides transformation in the nearly nanosized powders
3. "Synthesis of nanopowders by electric discharge assisted mechanical milling".