Bulk Smco5/Alpha-Fe Nanocomposite Permanent Magnets Fabricated By Mould-Free Joule-Heating Compaction

Bulk SmCo5/alpha-Fe nanocomposite magnets have been prepared using a Joule-heating compaction technique. Nearly fully dense bulk magnets are obtained by compacting the milled powders under a pressure of 2 GPa at temperatures above 400 degrees C. Structural analysis shows that the grain size of both the SmCo5 and the alpha-Fe phases is in the range of 10 to 15 nm when the compaction temperature is lower than 500 degrees C, which ensures effective interphase exchange coupling. A further increase in compaction temperature leads to significant grain growth and deterioration of magnetic properties. A maximum energy product of about 18.5 MGOe was obtained in the bulk SmCo5/alpha-Fe nanocomposite magnets, which is 90% higher than that of the single-phase counterpart prepared under the same conditions. (c) 2011 American Institute of Physics. [doi:10.1063/1.3563098]