Powdered Fe-based nanocrystalline cores: The powdered Fe-based nanocrystalline cores are made with crushed and annealed Fe-based nanocrystalline ribbons. The effective permeability of powdered Fe-based nanocrystalline cores ranges from 35 to 90. The characteristics of powdered Fe-based nanocrystalline cores at high frequency are superior to that of iron powder cores and Fe-Si-Al powder cores. The powdered Fe-based nanocrystalline cores have been used in PFC inductor, UPS power supply, high frequency switch power supply and so on.