We have produced nanocrystalline powders from iron, nickel, cobalt and
alloys, by fusion in a cryogenic medium. The use of refractory crucib
les being incompatible with the temperatures required we have used ele
ctromagnetic levitation. This process enables these metals to be broug
ht up to around 2000-degrees-C, and to obtain a powder production of s
everal grammes per minute. We have studied the parameters acting on th
e average particle diameter: temperature, height and nature of the cry
ogenic medium. The powders obtained are characterized by X-rays and Tr
ansmission Electron Microscopy. Their crystalline structure is compara
ble to that of powders obtained by conventional evaporation-condensati
on methods. We have also studied the compaction of powders obtained as
a function of pressure. The maximum relative density of the iron powd
ers was of 0.7 for a pressure of 2.56 GPa which is far less than that
obtained with micrometric powders under identical conditions. The sint
ering of powders starts from 160-degrees-C with a very large shrinkage
.