The cryogenic milling and milling in conjunction with dielectric barrier discharge plasma (DBDP) have been separately set up. The combined effect of low temperature and plasma on ball milling has been investigated by examining the refinement of particle size and grain size of iron powder using scanning electron microscopy, X-ray diffraction, and small angle X-ray scattering. It was found that the mean size of iron particles could reach 104nm only after 10 hours of ball milling in conjunction with DBDP, whereas a minimum average grain size of 8.4nm was obtained by cryomilling at -20℃; however, it is difficult to refine the particle size and grain size under the same milling condition in the absence of DBDP and cryogenic temperature.
Etching and oxidation were adopted to improve the frequency dependence of permeability of nanocrystalline Fe85-xCoxNb7B8 ribbons. The effect of etching and oxidation on the permeability spectrum of nanocrystalline Fe85-CoxNb7B8 ribbons was investigated. The relaxation frequency shifted to higher frequency end after etching and oxidation while the amplitude of μ1 was reduced at the same time. As a whole, μf0 rises and reflects the increasing of resistivity after etching and oxidation.
