Effect of compaction pressure on core loss in Fe-Ni powder cores for high frequency applications

This paper describes the effect of compaction pressure on the crystal structure and magnetic properties of Fe-Ni powder core to understand the correlation between core loss and compaction pressure. It was observed that the crystal structure of each core was a disordered γ-Fe-Ni phase. With an increase in compaction pressure, both saturation magnetization and relative part of permeability increased, while these values were lower than those of bulk values regardless of the compaction pressure, which might be attributed to the presence of defects, voids and air gaps within the core. The tendency of core loss to frequency is independent of the compaction pressure, but the core loss value is significantly influenced by it. Notably, the core compacted at a pressure of 1176 MPa exhibited the lowest core loss values, which might be ascribed to the suppression of eddy current in the core. These results suggest that careful optimization of the compaction process could markedly reduce core loss in Fe-Ni powder core.