Consolidation and magnetic properties of nanostructured Ni75Fe25

In the fabrication of nanostructured soft magnetic materials, powder processing is an attractive approach as it provides ability for mass production of bulk-volume magnetic components. In this approach, consolidating while retaining required nanostructure of the nanopowder is a big challenge. In this work, the as-synthesized Ni₇₅Fe₂₅ nanoparticles were consolidated by hot pressing. The results indicate that high packing density is achievable. In the hot press processing, two physical interactions are decisive in determining the magnetic softness of the material: internal demagnetizing effect caused by porosity and exchange coupling. This study demonstrates that in order to eliminate demagnetizing effect and to make the exchange coupling dominant, the nanopowders have to be over 95% dense.