Magnetic pulsed compaction of ferromagnetic nano-powders for soft-magnetic core

Densification of nanocrystalline Fe–6.5 wt.% Si powder with 20–40 μm particle size by uniaxial compaction and magnetic pulsed compaction was investigated in the temperature range of 23–400 °C and applied pressure range of 0.3–2.0 GPa. The microstructure of mechanically milled powder for 36 h showed a distribution of α-Fe phase 13–30 nm in size embedded in the matrix. The maximum relative density of Fe–6.5 wt.% Si green compact (core) was achieved more than 82%, by magnetic pulsed compaction (MPC) at room temperature under 2.0 GPa using annealed coarse powder (milled for 4 h), while it was less than 62% by a uniaxial static compaction. Finally, a remarkable effect of the compaction using the MPC process on the final density of Fe–Si alloy was measured in this research. The magnetic permeability of Fe–6.5 wt.% Si and Fe–6 wt.% Al–9 wt.% Si core is increased with the relative density increased.