Amorphous-derived superplasticity for high-density soft magnetic cores with reduced core loss

초록

Fe-based amorphous soft magnetic materials have emerged as promising candidates for high-frequency magnetic core applications, as microstructural modification can effectively suppress eddy current loss and thereby minimize the overall core loss. In this study, high-density soft magnetic cores were successfully fabricated using Fe75.5-x(C, Si, B, P)24.5(Cr, Al)x (x = 2.0 and 4.3) amorphous flakes. The amorphous-derived superplasticity enabled severe plastic deformation during sintering without crystallization, resulting in highly densified compacts with relative densities of 96.3 % and 98.0 % for the x = 2.0 and x = 4.3 specimens, respectively. This densification minimized degradation in saturation magnetic flux density and permeability, while maintaining acceptable coercivity. SiO2 insulation coatings significantly reduced the eddy current loss at 1000 Hz, thereby decreasing the core loss from 1.98 to 1.03 W/kg for x = 2.0 specimen and from 2.03 to 1.28 W/kg for x = 4.3 specimen after coating. The sintered cores also exhibited sufficient hardness. These findings highlight a promising processing route for achieving low-loss, high-performance soft magnetic materials by leveraging superplastic sintering of amorphous precursors.

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