Permeabiliteten hos mjuka magnetiska kompositer påverkas av många faktorer, såsom sammansättningen av magnetiska partiklar, partikelform, storlek, packningsdensitet, etc. Därför kan den justeras enligt driftsfrekvensen.
Magnetic powder cores are a typical example of soft magnetic composites. Now (early 21st century) some soft ferrites have been replaced in 20kHz to 100kHz and even 1MHz inductors. For example, FeSiAl magnetic powder core, the silicon content is 8.8 percent , the aluminum is 5.76 percent , and the rest is all iron. The particle size is 90-45μm, 45-32μm and 32-30μm. Silicone resin is used as a binder, and about 1 percent stearic acid is used as a lubricant. Under the pressure of 2t/cm2, a ring magnetic core of 1385 is made. In hydrogen, 673 degree K, 773 degree K, 873 degree K annealing to achieve permeability of 100, 300, 600. Low losses at 100kHz, have replaced soft ferrite and MPP powder cores in inductors.
