Comparison on refinement of iron powder by ball milling assisted by different external fields

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°C; 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.